diff --git a/package.json b/package.json
index 948c50c354..79f643dde1 100644
--- a/package.json
+++ b/package.json
@@ -142,6 +142,12 @@
       "*.dic.js"
     ],
     "rules": {
+      "@typescript-eslint/explicit-function-return-type": [
+        "warn",
+        {
+          "allowExpressions": true
+        }
+      ],
       "@typescript-eslint/no-empty-interface": "warn",
       "@typescript-eslint/no-explicit-any": "off",
       "@typescript-eslint/no-inferrable-types": "warn",
diff --git a/src/backend/index.ts b/src/backend/index.ts
index d81f53ae64..c3266860a5 100644
--- a/src/backend/index.ts
+++ b/src/backend/index.ts
@@ -109,11 +109,12 @@ const wordApi = new Api.WordApi(config, BASE_PATH, axiosInstance);
 
 // Backend controllers receiving a file via a "[FromForm] FileUpload fileUpload" param
 // have the internal fields expanded by openapi-generator as params in our Api.
+// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 function fileUpload(file: File) {
   return { file, filePath: "", name: "" };
 }
 
-function defaultOptions() {
+function defaultOptions(): object {
   return { headers: authHeader() };
 }
 
diff --git a/src/backend/tests/localStorage.test.tsx b/src/backend/tests/localStorage.test.tsx
index 6bfe8e2f75..31b02a86b1 100644
--- a/src/backend/tests/localStorage.test.tsx
+++ b/src/backend/tests/localStorage.test.tsx
@@ -32,7 +32,7 @@ afterAll(() => {
   }
 });
 
-function expectAllEmpty() {
+function expectAllEmpty(): void {
   expect(LocalStorage.getAvatar()).toEqual("");
   expect(LocalStorage.getClosedBanner()).toEqual("");
   expect(LocalStorage.getCurrentUser()).toEqual(undefined);
diff --git a/src/components/AnnouncementBanner/AnnouncementBanner.tsx b/src/components/AnnouncementBanner/AnnouncementBanner.tsx
index 4a6d838af8..5db0fffa96 100644
--- a/src/components/AnnouncementBanner/AnnouncementBanner.tsx
+++ b/src/components/AnnouncementBanner/AnnouncementBanner.tsx
@@ -3,6 +3,7 @@ import { Box, IconButton, Toolbar, Typography } from "@mui/material";
 import {
   CSSProperties,
   Fragment,
+  ReactElement,
   useCallback,
   useEffect,
   useState,
@@ -17,7 +18,7 @@ import { useAppSelector } from "types/hooks";
 import { Path } from "types/path";
 import theme, { themeColors } from "types/theme";
 
-export default function AnnouncementBanner() {
+export default function AnnouncementBanner(): ReactElement {
   const [banner, setBanner] = useState<string>("");
   const [margins, setMargins] = useState<CSSProperties>({});
 
@@ -40,7 +41,7 @@ export default function AnnouncementBanner() {
     });
   }, [loc, calculateMargins]);
 
-  function closeBanner() {
+  function closeBanner(): void {
     setClosedBanner(banner);
     setBanner("");
   }
diff --git a/src/components/App/AppLoggedIn.tsx b/src/components/App/AppLoggedIn.tsx
index 9b3ceee085..713866723c 100644
--- a/src/components/App/AppLoggedIn.tsx
+++ b/src/components/App/AppLoggedIn.tsx
@@ -57,7 +57,7 @@ export default function AppWithBar(): ReactElement {
     }
   }, [proj]);
 
-  const overrideThemeFont = (theme: Theme) =>
+  const overrideThemeFont = (theme: Theme): Theme =>
     styleOverrides
       ? createTheme({
           ...theme,
diff --git a/src/components/App/SignalRHub.tsx b/src/components/App/SignalRHub.tsx
index 7b829f8c5d..0606481cda 100644
--- a/src/components/App/SignalRHub.tsx
+++ b/src/components/App/SignalRHub.tsx
@@ -3,7 +3,13 @@ import {
   HubConnectionBuilder,
   HubConnectionState,
 } from "@microsoft/signalr";
-import { Fragment, useCallback, useEffect, useState } from "react";
+import {
+  Fragment,
+  ReactElement,
+  useCallback,
+  useEffect,
+  useState,
+} from "react";
 
 import { baseURL } from "backend";
 import { getUserId } from "backend/localStorage";
@@ -16,7 +22,7 @@ import { StoreState } from "types";
 import { useAppDispatch, useAppSelector } from "types/hooks";
 
 /** A central hub for monitoring export status on SignalR */
-export default function SignalRHub() {
+export default function SignalRHub(): ReactElement {
   const exportState = useAppSelector(
     (state: StoreState) => state.exportProjectState
   );
diff --git a/src/components/AppBar/tests/AppBarComponent.test.tsx b/src/components/AppBar/tests/AppBarComponent.test.tsx
index b58fc64f49..b1f9796539 100644
--- a/src/components/AppBar/tests/AppBarComponent.test.tsx
+++ b/src/components/AppBar/tests/AppBarComponent.test.tsx
@@ -18,7 +18,7 @@ jest.mock("backend", () => ({
 
 const mockStore = configureMockStore()(defaultState);
 
-function setMockFunctions() {
+function setMockFunctions(): void {
   mockGetUser.mockResolvedValue(mockUser);
 }
 
diff --git a/src/components/AppBar/tests/ProjectButtons.test.tsx b/src/components/AppBar/tests/ProjectButtons.test.tsx
index 186e422b3b..ed6060897c 100644
--- a/src/components/AppBar/tests/ProjectButtons.test.tsx
+++ b/src/components/AppBar/tests/ProjectButtons.test.tsx
@@ -1,6 +1,6 @@
 import { Button } from "@mui/material";
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -30,15 +30,15 @@ const mockProjectId = "proj-id";
 const mockProjectRoles: { [key: string]: string } = {};
 mockProjectRoles[mockProjectId] = "non-empty-string";
 
-let testRenderer: renderer.ReactTestRenderer;
+let testRenderer: ReactTestRenderer;
 
 const mockStore = configureMockStore()({
   currentProjectState: { project: { name: "" } },
 });
 
-const renderProjectButtons = async (path = Path.Root) => {
-  await renderer.act(async () => {
-    testRenderer = renderer.create(
+const renderProjectButtons = async (path = Path.Root): Promise<void> => {
+  await act(async () => {
+    testRenderer = create(
       <Provider store={mockStore}>
         <ProjectButtons currentTab={path} />
       </Provider>
diff --git a/src/components/AppBar/tests/UserMenu.test.tsx b/src/components/AppBar/tests/UserMenu.test.tsx
index 5a9c8189bf..3a34f8f562 100644
--- a/src/components/AppBar/tests/UserMenu.test.tsx
+++ b/src/components/AppBar/tests/UserMenu.test.tsx
@@ -1,6 +1,6 @@
 import { Button, MenuItem } from "@mui/material";
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import { act, create, ReactTestRenderer } from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -21,7 +21,7 @@ jest.mock("react-router-dom", () => ({
   useNavigate: jest.fn(),
 }));
 
-let testRenderer: renderer.ReactTestRenderer;
+let testRenderer: ReactTestRenderer;
 
 const mockStore = configureMockStore()();
 
@@ -30,7 +30,7 @@ const mockGetUserId = jest.fn();
 const mockUser = newUser();
 const mockUserId = "mockUserId";
 
-function setMockFunctions() {
+function setMockFunctions(): void {
   mockGetUser.mockResolvedValue(mockUser);
   mockGetUserId.mockReturnValue(mockUserId);
 }
@@ -41,9 +41,9 @@ beforeEach(() => {
 });
 
 describe("UserMenu", () => {
-  it("renders without crashing", () => {
-    renderer.act(() => {
-      testRenderer = renderer.create(
+  it("renders without crashing", async () => {
+    await act(async () => {
+      testRenderer = create(
         <Provider store={mockStore}>
           <UserMenu currentTab={Path.Root} />
         </Provider>
@@ -59,18 +59,18 @@ describe("UserMenu", () => {
     expect(await getIsAdmin()).toBeTruthy();
   });
 
-  it("UserMenuList has one more item for admins (Site Settings)", () => {
-    renderMenuList();
+  it("UserMenuList has one more item for admins (Site Settings)", async () => {
+    await renderMenuList();
     const normalMenuItems = testRenderer.root.findAllByType(MenuItem).length;
-    renderMenuList(true);
+    await renderMenuList(true);
     const adminMenuItems = testRenderer.root.findAllByType(MenuItem).length;
     expect(adminMenuItems).toBe(normalMenuItems + 1);
   });
 });
 
-function renderMenuList(isAdmin = false) {
-  renderer.act(() => {
-    testRenderer = renderer.create(
+async function renderMenuList(isAdmin = false): Promise<void> {
+  await act(async () => {
+    testRenderer = create(
       <Provider store={mockStore}>
         <UserMenuList isAdmin={isAdmin} onSelect={jest.fn()} />
       </Provider>
diff --git a/src/components/Buttons/FileInputButton.tsx b/src/components/Buttons/FileInputButton.tsx
index 3ca32fe9f3..75e75ed863 100644
--- a/src/components/Buttons/FileInputButton.tsx
+++ b/src/components/Buttons/FileInputButton.tsx
@@ -1,17 +1,17 @@
 import { Button } from "@mui/material";
 import { ButtonProps } from "@mui/material/Button";
-import React, { ReactElement } from "react";
+import { ReactElement, ReactNode } from "react";
 
 interface BrowseProps {
   updateFile: (file: File) => void;
   accept?: string;
-  children?: React.ReactNode;
+  children?: ReactNode;
   buttonProps?: ButtonProps;
 }
 
 // This button links to a set of functions
 export default function FileInputButton(props: BrowseProps): ReactElement {
-  function updateFirstFile(files: FileList) {
+  function updateFirstFile(files: FileList): void {
     const file = files[0];
     if (file) {
       props.updateFile(file);
@@ -19,7 +19,7 @@ export default function FileInputButton(props: BrowseProps): ReactElement {
   }
 
   return (
-    <React.Fragment>
+    <>
       {/* The actual file input element is hidden... */}
       <input
         id="file-input"
@@ -38,6 +38,6 @@ export default function FileInputButton(props: BrowseProps): ReactElement {
           {props.children}
         </Button>
       </label>
-    </React.Fragment>
+    </>
   );
 }
diff --git a/src/components/Buttons/PartOfSpeechButton.tsx b/src/components/Buttons/PartOfSpeechButton.tsx
index 23feb1158b..05db4aa1fb 100644
--- a/src/components/Buttons/PartOfSpeechButton.tsx
+++ b/src/components/Buttons/PartOfSpeechButton.tsx
@@ -32,7 +32,7 @@ export default function PartOfSpeech(props: PartOfSpeechProps): ReactElement {
     catGroupText
   );
 
-  const CatGroupButton = () => (
+  const CatGroupButton = (): ReactElement => (
     <IconButtonWithTooltip
       buttonId={props.buttonId}
       icon={<Hexagon fontSize="small" sx={{ color }} />}
diff --git a/src/components/DataEntry/DataEntryTable/EntryCellComponents/DeleteEntry.tsx b/src/components/DataEntry/DataEntryTable/EntryCellComponents/DeleteEntry.tsx
index f69dba7441..5e6377311c 100644
--- a/src/components/DataEntry/DataEntryTable/EntryCellComponents/DeleteEntry.tsx
+++ b/src/components/DataEntry/DataEntryTable/EntryCellComponents/DeleteEntry.tsx
@@ -1,6 +1,6 @@
 import { Delete } from "@mui/icons-material";
 import { IconButton, Tooltip } from "@mui/material";
-import React, { useState } from "react";
+import { ReactElement, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import { CancelConfirmDialog } from "components/Dialogs";
@@ -18,11 +18,11 @@ interface DeleteEntryProps {
 /**
  * A delete button
  */
-export default function DeleteEntry(props: DeleteEntryProps) {
+export default function DeleteEntry(props: DeleteEntryProps): ReactElement {
   const [open, setOpen] = useState<boolean>(false);
   const { t } = useTranslation();
 
-  function handleClick() {
+  function handleClick(): void {
     if (props.confirmId) {
       setOpen(true);
     } else {
@@ -31,7 +31,7 @@ export default function DeleteEntry(props: DeleteEntryProps) {
   }
 
   return (
-    <React.Fragment>
+    <>
       <Tooltip title={t("addWords.deleteRow")} placement="top">
         <IconButton
           tabIndex={-1}
@@ -53,6 +53,6 @@ export default function DeleteEntry(props: DeleteEntryProps) {
         buttonIdCancel="delete-word-cancel"
         buttonIdConfirm="delete-word-confirm"
       />
-    </React.Fragment>
+    </>
   );
 }
diff --git a/src/components/DataEntry/DataEntryTable/EntryCellComponents/EntryNote.tsx b/src/components/DataEntry/DataEntryTable/EntryCellComponents/EntryNote.tsx
index c80f1c2290..142a48e4d1 100644
--- a/src/components/DataEntry/DataEntryTable/EntryCellComponents/EntryNote.tsx
+++ b/src/components/DataEntry/DataEntryTable/EntryCellComponents/EntryNote.tsx
@@ -1,6 +1,6 @@
 import { AddComment, Comment } from "@mui/icons-material";
 import { IconButton, Tooltip } from "@mui/material";
-import React, { useState } from "react";
+import { ReactElement, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import { EditTextDialog } from "components/Dialogs";
@@ -14,12 +14,12 @@ interface EntryNoteProps {
 /**
  * A note adding/editing button
  */
-export default function EntryNote(props: EntryNoteProps) {
+export default function EntryNote(props: EntryNoteProps): ReactElement {
   const [noteOpen, setNoteOpen] = useState<boolean>(false);
   const { t } = useTranslation();
 
   return (
-    <React.Fragment>
+    <>
       <Tooltip
         title={props.noteText ? props.noteText : t("addWords.addNote")}
         placement="top"
@@ -42,6 +42,6 @@ export default function EntryNote(props: EntryNoteProps) {
         buttonIdConfirm="note-edit-confirm"
         textFieldId="note-text-field"
       />
-    </React.Fragment>
+    </>
   );
 }
diff --git a/src/components/DataEntry/DataEntryTable/EntryCellComponents/tests/EntryNote.test.tsx b/src/components/DataEntry/DataEntryTable/EntryCellComponents/tests/EntryNote.test.tsx
index bfe5e16b09..6f885f46a4 100644
--- a/src/components/DataEntry/DataEntryTable/EntryCellComponents/tests/EntryNote.test.tsx
+++ b/src/components/DataEntry/DataEntryTable/EntryCellComponents/tests/EntryNote.test.tsx
@@ -1,5 +1,10 @@
 import { AddComment, Comment } from "@mui/icons-material";
-import renderer from "react-test-renderer";
+import {
+  ReactTestInstance,
+  ReactTestRenderer,
+  act,
+  create,
+} from "react-test-renderer";
 
 import "tests/reactI18nextMock";
 
@@ -7,12 +12,12 @@ import EntryNote from "components/DataEntry/DataEntryTable/EntryCellComponents/E
 
 const mockText = "Test text";
 
-let testMaster: renderer.ReactTestRenderer;
-let testHandle: renderer.ReactTestInstance;
+let testMaster: ReactTestRenderer;
+let testHandle: ReactTestInstance;
 
-function renderWithText(text: string) {
-  renderer.act(() => {
-    testMaster = renderer.create(
+async function renderWithText(text: string): Promise<void> {
+  await act(async () => {
+    testMaster = create(
       <EntryNote noteText={text} updateNote={jest.fn()} buttonId="" />
     );
   });
@@ -20,14 +25,14 @@ function renderWithText(text: string) {
 }
 
 describe("DeleteEntry", () => {
-  it("renders without note", () => {
-    renderWithText("");
+  it("renders without note", async () => {
+    await renderWithText("");
     expect(testHandle.findAllByType(AddComment).length).toBe(1);
     expect(testHandle.findAllByType(Comment).length).toBe(0);
   });
 
-  it("renders with note", () => {
-    renderWithText(mockText);
+  it("renders with note", async () => {
+    await renderWithText(mockText);
     expect(testHandle.findAllByType(AddComment).length).toBe(0);
     expect(testHandle.findAllByType(Comment).length).toBe(1);
   });
diff --git a/src/components/DataEntry/DataEntryTable/NewEntry/SenseDialog.tsx b/src/components/DataEntry/DataEntryTable/NewEntry/SenseDialog.tsx
index 19cbb1c910..11132c97f4 100644
--- a/src/components/DataEntry/DataEntryTable/NewEntry/SenseDialog.tsx
+++ b/src/components/DataEntry/DataEntryTable/NewEntry/SenseDialog.tsx
@@ -54,7 +54,7 @@ interface SenseListProps {
   analysisLang: string;
 }
 
-export function SenseList(props: SenseListProps) {
+export function SenseList(props: SenseListProps): ReactElement {
   const { t } = useTranslation();
 
   const hasPartsOfSpeech = !!props.selectedWord.senses.find(
diff --git a/src/components/DataEntry/DataEntryTable/NewEntry/VernDialog.tsx b/src/components/DataEntry/DataEntryTable/NewEntry/VernDialog.tsx
index 82e08ae0d8..77e96dc084 100644
--- a/src/components/DataEntry/DataEntryTable/NewEntry/VernDialog.tsx
+++ b/src/components/DataEntry/DataEntryTable/NewEntry/VernDialog.tsx
@@ -54,7 +54,7 @@ interface VernListProps {
   analysisLang?: string;
 }
 
-export function VernList(props: VernListProps) {
+export function VernList(props: VernListProps): ReactElement {
   const { t } = useTranslation();
 
   const hasPartsOfSpeech = !!props.vernacularWords.find((w) =>
diff --git a/src/components/DataEntry/DataEntryTable/tests/RecentEntry.test.tsx b/src/components/DataEntry/DataEntryTable/tests/RecentEntry.test.tsx
index 0cd97a629a..fc8525608b 100644
--- a/src/components/DataEntry/DataEntryTable/tests/RecentEntry.test.tsx
+++ b/src/components/DataEntry/DataEntryTable/tests/RecentEntry.test.tsx
@@ -1,6 +1,11 @@
 import { StyledEngineProvider, ThemeProvider } from "@mui/material/styles";
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import {
+  ReactTestInstance,
+  ReactTestRenderer,
+  act,
+  create,
+} from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -38,12 +43,12 @@ const mockUpdateGloss = jest.fn();
 const mockUpdateNote = jest.fn();
 const mockUpdateVern = jest.fn();
 
-let testMaster: renderer.ReactTestRenderer;
-let testHandle: renderer.ReactTestInstance;
+let testMaster: ReactTestRenderer;
+let testHandle: ReactTestInstance;
 
-function renderWithWord(word: Word) {
-  renderer.act(() => {
-    testMaster = renderer.create(
+async function renderWithWord(word: Word): Promise<void> {
+  await act(async () => {
+    testMaster = create(
       <StyledEngineProvider injectFirst>
         <ThemeProvider theme={theme}>
           <Provider store={mockStore}>
@@ -75,14 +80,14 @@ beforeEach(() => {
 
 describe("ExistingEntry", () => {
   describe("component", () => {
-    it("renders recorder and no players", () => {
-      renderWithWord(mockWord);
+    it("renders recorder and no players", async () => {
+      await renderWithWord(mockWord);
       expect(testHandle.findAllByType(AudioPlayer).length).toEqual(0);
       expect(testHandle.findAllByType(AudioRecorder).length).toEqual(1);
     });
 
-    it("renders recorder and 3 players", () => {
-      renderWithWord({ ...mockWord, audio: ["a.wav", "b.wav", "c.wav"] });
+    it("renders recorder and 3 players", async () => {
+      await renderWithWord({ ...mockWord, audio: ["a.wav", "b.wav", "c.wav"] });
       expect(testHandle.findAllByType(AudioPlayer).length).toEqual(3);
       expect(testHandle.findAllByType(AudioRecorder).length).toEqual(1);
     });
@@ -90,10 +95,10 @@ describe("ExistingEntry", () => {
 
   describe("vernacular", () => {
     it("updates if changed", async () => {
-      renderWithWord(mockWord);
+      await renderWithWord(mockWord);
       testHandle = testHandle.findByType(VernWithSuggestions);
-      async function updateVernAndBlur(text: string) {
-        await renderer.act(async () => {
+      async function updateVernAndBlur(text: string): Promise<void> {
+        await act(async () => {
           await testHandle.props.updateVernField(text);
           await testHandle.props.onBlur();
         });
@@ -108,10 +113,10 @@ describe("ExistingEntry", () => {
 
   describe("gloss", () => {
     it("updates if changed", async () => {
-      renderWithWord(mockWord);
+      await renderWithWord(mockWord);
       testHandle = testHandle.findByType(GlossWithSuggestions);
-      async function updateGlossAndBlur(text: string) {
-        await renderer.act(async () => {
+      async function updateGlossAndBlur(text: string): Promise<void> {
+        await act(async () => {
           await testHandle.props.updateGlossField(text);
           await testHandle.props.onBlur();
         });
@@ -125,10 +130,10 @@ describe("ExistingEntry", () => {
   });
 
   describe("note", () => {
-    it("updates text", () => {
-      renderWithWord(mockWord);
+    it("updates text", async () => {
+      await renderWithWord(mockWord);
       testHandle = testHandle.findByType(EntryNote).findByType(EditTextDialog);
-      renderer.act(() => {
+      await act(async () => {
         testHandle.props.updateText(mockText);
       });
       expect(mockUpdateNote).toBeCalledWith(mockText);
diff --git a/src/components/DataEntry/DataEntryTable/tests/index.test.tsx b/src/components/DataEntry/DataEntryTable/tests/index.test.tsx
index c10380ebb4..e8e0e70342 100644
--- a/src/components/DataEntry/DataEntryTable/tests/index.test.tsx
+++ b/src/components/DataEntry/DataEntryTable/tests/index.test.tsx
@@ -387,7 +387,7 @@ describe("DataEntryTable", () => {
       const vern = "vern";
       const glossDef = "gloss";
       const noteText = "note";
-      act(() => {
+      await act(async () => {
         testHandle.props.setNewVern(vern);
         testHandle.props.setNewGloss(glossDef);
         testHandle.props.setNewNote(noteText);
diff --git a/src/components/Dialogs/ButtonConfirmation.tsx b/src/components/Dialogs/ButtonConfirmation.tsx
index 0c3f0d798d..c348b05ef5 100644
--- a/src/components/Dialogs/ButtonConfirmation.tsx
+++ b/src/components/Dialogs/ButtonConfirmation.tsx
@@ -30,7 +30,7 @@ export default function ButtonConfirmation(
   const [loading, setLoading] = useState<boolean>(false);
   const { t } = useTranslation();
 
-  async function onConfirm() {
+  async function onConfirm(): Promise<void> {
     setLoading(true);
     await props.onConfirm();
     setLoading(false);
diff --git a/src/components/Dialogs/DeleteEditTextDialog.tsx b/src/components/Dialogs/DeleteEditTextDialog.tsx
index afb2faf7ec..afbc9c8a87 100644
--- a/src/components/Dialogs/DeleteEditTextDialog.tsx
+++ b/src/components/Dialogs/DeleteEditTextDialog.tsx
@@ -40,12 +40,12 @@ export default function DeleteEditTextDialog(
   const [text, setText] = useState<string>(props.text);
   const { t } = useTranslation();
 
-  function onCancel() {
+  function onCancel(): void {
     setText(props.text);
     props.close();
   }
 
-  function onDelete() {
+  function onDelete(): void {
     setText(props.text);
     if (props.onDelete) {
       props.onDelete();
@@ -53,20 +53,23 @@ export default function DeleteEditTextDialog(
     props.close();
   }
 
-  async function onSave() {
+  async function onSave(): Promise<void> {
     setLoading(true);
     await props.updateText(text);
     setLoading(false);
     props.close();
   }
 
-  function escapeClose(_: any, reason: "backdropClick" | "escapeKeyDown") {
+  function escapeClose(
+    _: any,
+    reason: "backdropClick" | "escapeKeyDown"
+  ): void {
     if (reason === "escapeKeyDown") {
       onCancel();
     }
   }
 
-  function confirmIfEnter(event: React.KeyboardEvent<any>) {
+  function confirmIfEnter(event: React.KeyboardEvent<any>): void {
     if (event.key === Key.Enter) {
       onSave();
     }
diff --git a/src/components/Dialogs/EditTextDialog.tsx b/src/components/Dialogs/EditTextDialog.tsx
index b891c283fc..976a3c4d88 100644
--- a/src/components/Dialogs/EditTextDialog.tsx
+++ b/src/components/Dialogs/EditTextDialog.tsx
@@ -35,25 +35,28 @@ export default function EditTextDialog(
   const [text, setText] = useState<string>(props.text);
   const { t } = useTranslation();
 
-  async function onConfirm() {
+  async function onConfirm(): Promise<void> {
     props.close();
     if (text !== props.text) {
       await props.updateText(text);
     }
   }
 
-  function onCancel() {
+  function onCancel(): void {
     setText(props.text);
     props.close();
   }
 
-  function escapeClose(_: any, reason: "backdropClick" | "escapeKeyDown") {
+  function escapeClose(
+    _: any,
+    reason: "backdropClick" | "escapeKeyDown"
+  ): void {
     if (reason === "escapeKeyDown") {
       props.close();
     }
   }
 
-  function confirmIfEnter(event: React.KeyboardEvent<any>) {
+  function confirmIfEnter(event: React.KeyboardEvent<any>): void {
     if (event.key === Key.Enter) {
       onConfirm();
     }
diff --git a/src/components/GoalTimeline/Redux/GoalActions.ts b/src/components/GoalTimeline/Redux/GoalActions.ts
index dce3840252..66db597cc0 100644
--- a/src/components/GoalTimeline/Redux/GoalActions.ts
+++ b/src/components/GoalTimeline/Redux/GoalActions.ts
@@ -216,7 +216,7 @@ export async function loadGoalData(goalType: GoalType): Promise<Word[][]> {
   }
 }
 
-async function saveCurrentStep(goal: Goal) {
+async function saveCurrentStep(goal: Goal): Promise<void> {
   const userEditId = getUserEditId();
   if (userEditId) {
     const step = goal.steps[goal.currentStep];
diff --git a/src/components/GoalTimeline/index.tsx b/src/components/GoalTimeline/index.tsx
index 93c6074935..b354192fe7 100644
--- a/src/components/GoalTimeline/index.tsx
+++ b/src/components/GoalTimeline/index.tsx
@@ -68,7 +68,8 @@ export default function GoalTimeline(): ReactElement {
     (state: StoreState) => state.goalsState
   );
 
-  const chooseGoal = (goal: Goal) => dispatch(asyncAddGoal(goal));
+  const chooseGoal = (goal: Goal): Promise<void> =>
+    dispatch(asyncAddGoal(goal));
 
   const [availableGoalTypes, setAvailableGoalTypes] = useState<GoalType[]>([]);
   const [suggestedGoalTypes, setSuggestedGoalTypes] = useState<GoalType[]>([]);
@@ -86,7 +87,7 @@ export default function GoalTimeline(): ReactElement {
       dispatch(asyncGetUserEdits());
       setLoaded(true);
     }
-    const updateHasGraylist = async () =>
+    const updateHasGraylist = async (): Promise<void> =>
       setHasGraylist(
         await getGraylistEntries(1).then((res) => res.length !== 0)
       );
diff --git a/src/components/GoalTimeline/tests/GoalRedux.test.tsx b/src/components/GoalTimeline/tests/GoalRedux.test.tsx
index 5af9ca0bc0..b6d1d03ff1 100644
--- a/src/components/GoalTimeline/tests/GoalRedux.test.tsx
+++ b/src/components/GoalTimeline/tests/GoalRedux.test.tsx
@@ -61,7 +61,7 @@ const mockGetUser = jest.fn();
 const mockGetUserEditById = jest.fn();
 const mockNavigate = jest.fn();
 const mockUpdateUser = jest.fn();
-function setMockFunctions() {
+function setMockFunctions(): void {
   mockAddGoalToUserEdit.mockResolvedValue(0);
   mockAddStepToGoal.mockResolvedValue(0);
   mockCreateUserEdit.mockResolvedValue(mockUser);
@@ -108,7 +108,7 @@ const mockUser = newUser("First Last", "username");
 mockUser.id = mockUserId;
 mockUser.workedProjects[mockProjectId] = mockUserEditId;
 
-function setupLocalStorage() {
+function setupLocalStorage(): void {
   LocalStorage.setCurrentUser(mockUser);
   LocalStorage.setProjectId(mockProjectId);
 }
diff --git a/src/components/Login/LoginPage/LoginComponent.tsx b/src/components/Login/LoginPage/LoginComponent.tsx
index f9b02ef6be..3291d02cff 100644
--- a/src/components/Login/LoginPage/LoginComponent.tsx
+++ b/src/components/Login/LoginPage/LoginComponent.tsx
@@ -9,7 +9,7 @@ import {
   TextField,
   Typography,
 } from "@mui/material";
-import { Component } from "react";
+import { Component, ReactElement } from "react";
 import { withTranslation, WithTranslation } from "react-i18next";
 
 import { BannerType } from "api/models";
@@ -71,7 +71,7 @@ export class Login extends Component<LoginProps, LoginState> {
     };
   }
 
-  componentDidMount() {
+  componentDidMount(): void {
     this.props.reset();
     getBannerText(BannerType.Login).then((loginBanner) =>
       this.setState({ loginBanner })
@@ -84,13 +84,13 @@ export class Login extends Component<LoginProps, LoginState> {
       HTMLTextAreaElement | HTMLInputElement | HTMLSelectElement
     >,
     field: K
-  ) {
+  ): void {
     const value = e.target.value;
 
     this.setState({ [field]: value } as Pick<LoginState, K>);
   }
 
-  login(e: React.FormEvent<EventTarget>) {
+  login(e: React.FormEvent<EventTarget>): void {
     e.preventDefault();
 
     const username: string = this.state.username.trim();
@@ -105,7 +105,7 @@ export class Login extends Component<LoginProps, LoginState> {
     }
   }
 
-  render() {
+  render(): ReactElement {
     return (
       <Grid container justifyContent="center">
         <Card style={{ width: 450 }}>
diff --git a/src/components/Login/LoginPage/tests/LoginComponent.test.tsx b/src/components/Login/LoginPage/tests/LoginComponent.test.tsx
index 2fbfd09627..45ee12c976 100644
--- a/src/components/Login/LoginPage/tests/LoginComponent.test.tsx
+++ b/src/components/Login/LoginPage/tests/LoginComponent.test.tsx
@@ -60,7 +60,7 @@ function testLogin(
   password: string,
   goodUsername: boolean,
   goodPassword: boolean
-) {
+): void {
   loginHandle.instance.setState({ username, password });
   loginHandle.instance.login(MOCK_EVENT);
   expect(loginHandle.instance.state.error).toEqual({
diff --git a/src/components/Login/SignUpPage/SignUpComponent.tsx b/src/components/Login/SignUpPage/SignUpComponent.tsx
index 5a7903f5ab..d06f888c6e 100644
--- a/src/components/Login/SignUpPage/SignUpComponent.tsx
+++ b/src/components/Login/SignUpPage/SignUpComponent.tsx
@@ -7,7 +7,7 @@ import {
   TextField,
   Typography,
 } from "@mui/material";
-import { Component } from "react";
+import { Component, ReactElement } from "react";
 import { withTranslation, WithTranslation } from "react-i18next";
 
 import router from "browserRouter";
@@ -86,7 +86,7 @@ export class SignUp extends Component<SignUpProps, SignUpState> {
     };
   }
 
-  componentDidMount() {
+  componentDidMount(): void {
     const search = window.location.search;
     const email = new URLSearchParams(search).get("email");
     if (email) {
@@ -101,7 +101,7 @@ export class SignUp extends Component<SignUpProps, SignUpState> {
       HTMLTextAreaElement | HTMLInputElement | HTMLSelectElement
     >,
     field: K
-  ) {
+  ): void {
     const value = e.target.value;
     this.setState({ [field]: value } as Pick<SignUpState, K>);
     this.setState((prevState) => ({
@@ -109,7 +109,7 @@ export class SignUp extends Component<SignUpProps, SignUpState> {
     }));
   }
 
-  async checkUsername() {
+  async checkUsername(): Promise<void> {
     if (!meetsUsernameRequirements(this.state.username)) {
       this.setState((prevState) => ({
         error: { ...prevState.error, username: true },
@@ -117,7 +117,7 @@ export class SignUp extends Component<SignUpProps, SignUpState> {
     }
   }
 
-  async signUp(e: React.FormEvent<HTMLFormElement>) {
+  async signUp(e: React.FormEvent<HTMLFormElement>): Promise<void> {
     e.preventDefault();
     const name = this.state.name.trim();
     const username = this.state.username.trim();
@@ -146,7 +146,7 @@ export class SignUp extends Component<SignUpProps, SignUpState> {
     }
   }
 
-  render() {
+  render(): ReactElement {
     return (
       <Grid container justifyContent="center">
         <Card style={{ width: 450 }}>
diff --git a/src/components/Login/SignUpPage/index.ts b/src/components/Login/SignUpPage/index.ts
index 598a46ac06..f3bbe065e6 100644
--- a/src/components/Login/SignUpPage/index.ts
+++ b/src/components/Login/SignUpPage/index.ts
@@ -16,6 +16,7 @@ function mapStateToProps(state: StoreState): SignUpStateProps {
   };
 }
 
+// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 function mapDispatchToProps(dispatch: StoreStateDispatch) {
   return {
     signUp: (
diff --git a/src/components/Login/SignUpPage/tests/SignUpComponent.test.tsx b/src/components/Login/SignUpPage/tests/SignUpComponent.test.tsx
index cb092f7566..84df8b4651 100644
--- a/src/components/Login/SignUpPage/tests/SignUpComponent.test.tsx
+++ b/src/components/Login/SignUpPage/tests/SignUpComponent.test.tsx
@@ -98,7 +98,7 @@ async function testSignUp(
   error_email: boolean,
   error_password: boolean,
   error_confirmPassword: boolean
-) {
+): Promise<void> {
   signUpHandle.instance.setState({
     name,
     username,
diff --git a/src/components/Login/tests/LoginActions.test.tsx b/src/components/Login/tests/LoginActions.test.tsx
index 0c53288cac..587f4762a2 100644
--- a/src/components/Login/tests/LoginActions.test.tsx
+++ b/src/components/Login/tests/LoginActions.test.tsx
@@ -175,7 +175,7 @@ describe("LoginAction", () => {
 function testActionCreatorAgainst(
   LoginAction: (name: string) => UserAction,
   type: LoginType
-) {
+): void {
   expect(LoginAction(mockUser.username)).toEqual({
     type: type,
     payload: { username: mockUser.username },
diff --git a/src/components/PageNotFound/component.tsx b/src/components/PageNotFound/component.tsx
index 12b178ac1f..b09d68ff75 100644
--- a/src/components/PageNotFound/component.tsx
+++ b/src/components/PageNotFound/component.tsx
@@ -1,5 +1,5 @@
 import { Typography } from "@mui/material";
-import React from "react";
+import { ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 import { useNavigate } from "react-router-dom";
 
@@ -10,12 +10,12 @@ import { Path } from "types/path";
  * A custom 404 page that should be displayed anytime the user tries to navigate
  * to a nonexistent route.
  */
-export default function PageNotFound() {
+export default function PageNotFound(): ReactElement {
   const { t } = useTranslation();
   const navigate = useNavigate();
 
   return (
-    <React.Fragment>
+    <>
       <Typography variant="h4" style={{ textAlign: "center" }}>
         {t("generic.404Title")}
       </Typography>
@@ -30,6 +30,6 @@ export default function PageNotFound() {
       <Typography variant="h5" style={{ textAlign: "center" }}>
         {t("generic.404Text")}
       </Typography>
-    </React.Fragment>
+    </>
   );
 }
diff --git a/src/components/ProjectExport/DownloadButton.tsx b/src/components/ProjectExport/DownloadButton.tsx
index d7e4ae27ba..ce844d3a90 100644
--- a/src/components/ProjectExport/DownloadButton.tsx
+++ b/src/components/ProjectExport/DownloadButton.tsx
@@ -21,7 +21,7 @@ import { useAppDispatch, useAppSelector } from "types/hooks";
 import { themeColors } from "types/theme";
 import { getNowDateTimeString } from "utilities/utilities";
 
-function makeExportName(projectName: string) {
+function makeExportName(projectName: string): string {
   return `${projectName}_${getNowDateTimeString()}.zip`;
 }
 
@@ -104,7 +104,7 @@ export default function DownloadButton(
     }
   }
 
-  function iconColor() {
+  function iconColor(): `#${string}` {
     return exportState.status === ExportStatus.Failure
       ? themeColors.error
       : props.colorSecondary
diff --git a/src/components/ProjectExport/ExportButton.tsx b/src/components/ProjectExport/ExportButton.tsx
index edfd0ab8d8..4b17e033f0 100644
--- a/src/components/ProjectExport/ExportButton.tsx
+++ b/src/components/ProjectExport/ExportButton.tsx
@@ -1,5 +1,6 @@
 import { ButtonProps } from "@mui/material/Button";
 import { enqueueSnackbar } from "notistack";
+import { ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 
 import { isFrontierNonempty } from "backend";
@@ -15,11 +16,11 @@ interface ExportButtonProps {
 }
 
 /** A button for exporting project to Lift file */
-export default function ExportButton(props: ExportButtonProps) {
+export default function ExportButton(props: ExportButtonProps): ReactElement {
   const dispatch = useAppDispatch();
   const { t } = useTranslation();
 
-  async function exportProj() {
+  async function exportProj(): Promise<void> {
     await isFrontierNonempty(props.projectId).then(async (isNonempty) => {
       if (isNonempty) {
         await dispatch(asyncExportProject(props.projectId));
diff --git a/src/components/ProjectScreen/CreateProject/tests/CreateProjectComponent.test.tsx b/src/components/ProjectScreen/CreateProject/tests/CreateProjectComponent.test.tsx
index bec78a8c57..b39d3c42d2 100644
--- a/src/components/ProjectScreen/CreateProject/tests/CreateProjectComponent.test.tsx
+++ b/src/components/ProjectScreen/CreateProject/tests/CreateProjectComponent.test.tsx
@@ -1,6 +1,11 @@
 import { LanguagePicker } from "mui-language-picker";
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import {
+  ReactTestInstance,
+  ReactTestRenderer,
+  act,
+  create,
+} from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -30,18 +35,22 @@ const mockState = {
 };
 const mockStore = createMockStore(mockState);
 
-const mockEvent = (value = "") => ({
-  preventDefault: jest.fn(),
+const mockChangeEvent = (
+  value: string
+): { target: Partial<EventTarget & HTMLSelectElement> } => ({
   target: { value },
 });
+const mockSubmitEvent = (): Partial<React.FormEvent<HTMLFormElement>> => ({
+  preventDefault: jest.fn(),
+});
 
-let projectMaster: renderer.ReactTestRenderer;
-let projectHandle: renderer.ReactTestInstance;
+let projectMaster: ReactTestRenderer;
+let projectHandle: ReactTestInstance;
 4;
 
 beforeAll(async () => {
-  await renderer.act(async () => {
-    projectMaster = renderer.create(
+  await act(async () => {
+    projectMaster = create(
       <Provider store={mockStore}>
         <CreateProject />
       </Provider>
@@ -59,22 +68,26 @@ describe("CreateProject", () => {
     const nameField = projectHandle.findByProps({ id: fieldIdName });
     expect(nameField.props.error).toBeFalsy();
 
-    await renderer.act(async () => {
-      projectHandle.findByProps({ id: formId }).props.onSubmit(mockEvent());
+    await act(async () => {
+      projectHandle
+        .findByProps({ id: formId })
+        .props.onSubmit(mockSubmitEvent());
     });
     expect(nameField.props.error).toBeTruthy();
   });
 
   it("errors on taken name", async () => {
     const nameField = projectHandle.findByProps({ id: fieldIdName });
-    await renderer.act(async () => {
-      nameField.props.onChange(mockEvent("non-empty"));
+    await act(async () => {
+      nameField.props.onChange(mockChangeEvent("non-empty-value"));
     });
     expect(nameField.props.error).toBeFalsy();
 
     mockProjectDuplicateCheck.mockResolvedValueOnce(true);
-    await renderer.act(async () => {
-      projectHandle.findByProps({ id: formId }).props.onSubmit(mockEvent());
+    await act(async () => {
+      projectHandle
+        .findByProps({ id: formId })
+        .props.onSubmit(mockSubmitEvent());
     });
     expect(nameField.props.error).toBeTruthy();
   });
@@ -85,7 +98,7 @@ describe("CreateProject", () => {
     const langPickers = projectHandle.findAllByType(LanguagePicker);
     expect(langPickers).toHaveLength(2);
 
-    await renderer.act(async () => {
+    await act(async () => {
       langPickers[0].props.setCode("non-empty");
     });
     expect(button.props.disabled).toBeFalsy();
@@ -97,7 +110,7 @@ describe("CreateProject", () => {
 
     // File with no writing systems only disables analysis lang picker.
     mockUploadLiftAndGetWritingSystems.mockResolvedValueOnce([]);
-    await renderer.act(async () => {
+    await act(async () => {
       button.props.updateFile(new File([], ""));
     });
     expect(projectHandle.findAllByType(LanguagePicker)).toHaveLength(1);
@@ -106,7 +119,7 @@ describe("CreateProject", () => {
     mockUploadLiftAndGetWritingSystems.mockResolvedValueOnce([
       newWritingSystem(),
     ]);
-    await renderer.act(async () => {
+    await act(async () => {
       button.props.updateFile(new File([], "oneLang"));
     });
     expect(projectHandle.findAllByType(LanguagePicker)).toHaveLength(0);
@@ -116,7 +129,7 @@ describe("CreateProject", () => {
     const button = projectHandle.findByType(FileInputButton);
     const langs = [newWritingSystem("redLang"), newWritingSystem("blueLang")];
     mockUploadLiftAndGetWritingSystems.mockResolvedValueOnce(langs);
-    await renderer.act(async () => {
+    await act(async () => {
       button.props.updateFile(new File([], "twoLang"));
     });
     const vernSelect = projectHandle.findByProps({ id: selectIdVern });
diff --git a/src/components/ProjectSettings/ProjectArchive.tsx b/src/components/ProjectSettings/ProjectArchive.tsx
index 4dc16374a3..b52b461676 100644
--- a/src/components/ProjectSettings/ProjectArchive.tsx
+++ b/src/components/ProjectSettings/ProjectArchive.tsx
@@ -1,6 +1,6 @@
 import { Button } from "@mui/material";
 import { ButtonProps } from "@mui/material/Button";
-import { useState } from "react";
+import { ReactElement, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import { archiveProject, restoreProject } from "backend";
@@ -17,25 +17,20 @@ interface ProjectArchiveProps extends ButtonProps {
 /**
  * Button for archiving/restoring project (changing isActive)
  */
-export default function ProjectArchive(props: ProjectArchiveProps) {
+export default function ProjectArchive(
+  props: ProjectArchiveProps
+): ReactElement {
   const [open, setOpen] = useState(false);
   const { t } = useTranslation();
 
-  async function updateProj() {
+  async function updateProj(): Promise<void> {
     if (props.archive) {
       await archiveProject(props.projectId);
     } else {
       await restoreProject(props.projectId);
     }
-    handleClose();
-    await props.updateParent();
-  }
-
-  function handleOpen() {
-    setOpen(true);
-  }
-  function handleClose() {
     setOpen(false);
+    await props.updateParent();
   }
 
   return (
@@ -43,7 +38,7 @@ export default function ProjectArchive(props: ProjectArchiveProps) {
       <Button
         variant="contained"
         color={props.warn ? "secondary" : "primary"}
-        onClick={handleOpen}
+        onClick={() => setOpen(true)}
         id={`proj-${props.projectId}-${props.archive ? "archive" : "restore"}`}
         style={props.warn ? { color: themeColors.error } : {}}
       >
@@ -57,7 +52,7 @@ export default function ProjectArchive(props: ProjectArchiveProps) {
             : "siteSettings.restoreProjectText"
         }
         titleId="buttons.proceedWithCaution"
-        onClose={handleClose}
+        onClose={() => setOpen(false)}
         onConfirm={updateProj}
         buttonIdClose={`proj-${props.projectId}-${
           props.archive ? "archive" : "restore"
diff --git a/src/components/ProjectSettings/ProjectSelect.tsx b/src/components/ProjectSettings/ProjectSelect.tsx
index ba434eb186..b3b99ff8c5 100644
--- a/src/components/ProjectSettings/ProjectSelect.tsx
+++ b/src/components/ProjectSettings/ProjectSelect.tsx
@@ -18,7 +18,7 @@ export default function ProjectSelect(
     }
   }, [props.project.name]);
 
-  const handleChange = (e: SelectChangeEvent) => {
+  const handleChange = (e: SelectChangeEvent): void => {
     if (e.target.name === props.project.name) {
       return;
     }
diff --git a/src/components/ProjectSettings/index.tsx b/src/components/ProjectSettings/index.tsx
index c9db31f36c..a0fab81c71 100644
--- a/src/components/ProjectSettings/index.tsx
+++ b/src/components/ProjectSettings/index.tsx
@@ -74,7 +74,7 @@ export enum Setting {
   Users = "SettingUsers",
 }
 
-export default function ProjectSettingsComponent() {
+export default function ProjectSettingsComponent(): ReactElement {
   const dispatch = useAppDispatch();
   const project = useAppSelector(
     (state: StoreState) => state.currentProjectState.project
diff --git a/src/components/ProjectSettings/tests/ProjectSelect.test.tsx b/src/components/ProjectSettings/tests/ProjectSelect.test.tsx
index ec98bf0405..b3dbb2fc5b 100644
--- a/src/components/ProjectSettings/tests/ProjectSelect.test.tsx
+++ b/src/components/ProjectSettings/tests/ProjectSelect.test.tsx
@@ -1,5 +1,5 @@
 import { Select } from "@mui/material";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 
 import ProjectSelect from "components/ProjectSettings/ProjectSelect";
 import { newProject, randomProject } from "types/project";
@@ -15,11 +15,11 @@ const mockGetAllActiveProjectsByUser = jest.fn();
 
 const mockProjects = [randomProject(), randomProject(), randomProject()];
 
-let selectMaster: renderer.ReactTestRenderer;
+let selectMaster: ReactTestRenderer;
 
-const renderSwitch = async (proj = newProject()) => {
-  await renderer.act(async () => {
-    selectMaster = renderer.create(
+const renderSwitch = async (proj = newProject()): Promise<void> => {
+  await act(async () => {
+    selectMaster = create(
       <ProjectSelect project={proj} setProject={jest.fn()} />
     );
   });
diff --git a/src/components/ProjectSettings/tests/index.test.tsx b/src/components/ProjectSettings/tests/index.test.tsx
index 7147ac151d..b3cf75cbc9 100644
--- a/src/components/ProjectSettings/tests/index.test.tsx
+++ b/src/components/ProjectSettings/tests/index.test.tsx
@@ -3,6 +3,7 @@ import { act, cleanup, render, screen } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
 import { match } from "css-mediaquery";
 import { Provider } from "react-redux";
+import { Store } from "redux";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -39,7 +40,7 @@ jest.mock("types/hooks", () => {
 
 const mockGetCurrentPermissions = jest.fn();
 
-const createMockStore = (hasSchedule = false) => {
+const createMockStore = (hasSchedule = false): Store => {
   const project = randomProject();
   if (hasSchedule) {
     project.workshopSchedule = [new Date().toString()];
@@ -50,7 +51,7 @@ const createMockStore = (hasSchedule = false) => {
   });
 };
 
-const updateProjSettings = async (hasSchedule = false) => {
+const updateProjSettings = async (hasSchedule = false): Promise<void> => {
   await act(async () => {
     // For this update to trigger a permissions refresh, project.id must change.
     // This is accomplished by randomProject() in createMockStore().
@@ -62,7 +63,7 @@ const updateProjSettings = async (hasSchedule = false) => {
   });
 };
 
-const resetMocks = () => {
+const resetMocks = (): void => {
   jest.clearAllMocks();
   mockGetCurrentPermissions.mockResolvedValue([]);
 };
diff --git a/src/components/Pronunciations/tests/PronunciationsBackend.test.tsx b/src/components/Pronunciations/tests/PronunciationsBackend.test.tsx
index e90192cb97..9e5f5b4ef4 100644
--- a/src/components/Pronunciations/tests/PronunciationsBackend.test.tsx
+++ b/src/components/Pronunciations/tests/PronunciationsBackend.test.tsx
@@ -1,6 +1,6 @@
 import { StyledEngineProvider, ThemeProvider } from "@mui/material/styles";
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -18,13 +18,15 @@ jest
 jest.mock("components/Pronunciations/Recorder");
 
 // Test variables
-let testRenderer: renderer.ReactTestRenderer;
+let testRenderer: ReactTestRenderer;
 const mockAudio = ["a.wav", "b.wav"];
 const mockStore = configureMockStore()({ pronunciationsState });
 
-const renderPronunciationsBackend = async (withRecord: boolean) => {
-  await renderer.act(async () => {
-    testRenderer = renderer.create(
+const renderPronunciationsBackend = async (
+  withRecord: boolean
+): Promise<void> => {
+  await act(async () => {
+    testRenderer = create(
       <StyledEngineProvider injectFirst>
         <ThemeProvider theme={theme}>
           <Provider store={mockStore}>
diff --git a/src/components/SiteSettings/ProjectManagement/ProjectUsersButtonWithConfirmation.tsx b/src/components/SiteSettings/ProjectManagement/ProjectUsersButtonWithConfirmation.tsx
index 42f49a3e93..321e04abb5 100644
--- a/src/components/SiteSettings/ProjectManagement/ProjectUsersButtonWithConfirmation.tsx
+++ b/src/components/SiteSettings/ProjectManagement/ProjectUsersButtonWithConfirmation.tsx
@@ -8,7 +8,7 @@ import {
   IconButton,
   Typography,
 } from "@mui/material";
-import { useEffect, useState } from "react";
+import { ReactElement, useEffect, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import { asyncRefreshProjectUsers } from "components/Project/ProjectActions";
@@ -26,7 +26,7 @@ interface ProjectUsersButtonWithConfirmationProps {
  */
 export default function ProjectUsersButtonWithConfirmation(
   props: ProjectUsersButtonWithConfirmationProps
-) {
+): ReactElement {
   const [open, setOpen] = useState(false);
   const { t } = useTranslation();
 
@@ -58,7 +58,7 @@ export default function ProjectUsersButtonWithConfirmation(
   );
 }
 
-function ProjUsersDialogContent(props: { projectId: string }) {
+function ProjUsersDialogContent(props: { projectId: string }): ReactElement {
   const dispatch = useAppDispatch();
 
   const { t } = useTranslation();
diff --git a/src/components/SiteSettings/ProjectManagement/index.tsx b/src/components/SiteSettings/ProjectManagement/index.tsx
index ca73ea4868..6c84d22077 100644
--- a/src/components/SiteSettings/ProjectManagement/index.tsx
+++ b/src/components/SiteSettings/ProjectManagement/index.tsx
@@ -8,7 +8,7 @@ import ProjectArchive from "components/ProjectSettings/ProjectArchive";
 import ProjectUsersButtonWithConfirmation from "components/SiteSettings/ProjectManagement/ProjectUsersButtonWithConfirmation";
 import theme from "types/theme";
 
-export default function ProjectManagement() {
+export default function ProjectManagement(): ReactElement {
   const [allProjects, setAllProjects] = useState<Project[]>([]);
   const [activeProjects, setActiveProjects] = useState<Project[]>([]);
   const [archivedProjects, setArchivedProjects] = useState<Project[]>([]);
diff --git a/src/components/Statistics/DomainStatistics.tsx b/src/components/Statistics/DomainStatistics.tsx
index 3ba8baea79..3d0132b245 100644
--- a/src/components/Statistics/DomainStatistics.tsx
+++ b/src/components/Statistics/DomainStatistics.tsx
@@ -18,7 +18,7 @@ export default function DomainStatistics(
   );
 
   useEffect(() => {
-    const updateStatisticList = async () => {
+    const updateStatisticList = async (): Promise<void> => {
       const counts = await getStatisticsCounts(
         LocalStorage.getProjectId(),
         props.lang
diff --git a/src/components/Statistics/LineChartComponent.tsx b/src/components/Statistics/LineChartComponent.tsx
index e4f5d10fed..e84931c442 100644
--- a/src/components/Statistics/LineChartComponent.tsx
+++ b/src/components/Statistics/LineChartComponent.tsx
@@ -9,7 +9,7 @@ import {
   PointElement,
 } from "chart.js";
 import distinctColors from "distinct-colors";
-import { useEffect, useState } from "react";
+import { ReactElement, useEffect, useState } from "react";
 import { Line } from "react-chartjs-2";
 import { useTranslation } from "react-i18next";
 
@@ -55,11 +55,13 @@ function FilteredData(numbers: number[]): number[] {
   return numbers.map((num) => (num ? num : NaN));
 }
 
-export default function LineChartComponent(props: LineChartProps) {
+export default function LineChartComponent(
+  props: LineChartProps
+): ReactElement {
   const [chartData, setChartData] = useState(getDefaultProps());
 
   useEffect(() => {
-    const updateChartList = async () => {
+    const updateChartList = async (): Promise<void> => {
       const tempData = await props.fetchData();
       const newChartData = getDefaultProps();
       if (tempData) {
diff --git a/src/components/Statistics/ProgressBar/LinearProgressBar.tsx b/src/components/Statistics/ProgressBar/LinearProgressBar.tsx
index 54038b2a63..b336dff075 100644
--- a/src/components/Statistics/ProgressBar/LinearProgressBar.tsx
+++ b/src/components/Statistics/ProgressBar/LinearProgressBar.tsx
@@ -1,13 +1,16 @@
 import Box from "@mui/material/Box";
 import LinearProgress from "@mui/material/LinearProgress";
 import Typography from "@mui/material/Typography";
+import { ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 
 interface ProgressBarProps {
   value: number;
 }
 
-export default function LinearProgressWithLabel(props: ProgressBarProps) {
+export default function LinearProgressWithLabel(
+  props: ProgressBarProps
+): ReactElement {
   const { t } = useTranslation();
   return (
     <Box sx={{ display: "flex", alignItems: "center", width: "50%" }}>
diff --git a/src/components/Statistics/ProgressBar/ProgressBarComponent.tsx b/src/components/Statistics/ProgressBar/ProgressBarComponent.tsx
index f8e3696e23..f2a76f293d 100644
--- a/src/components/Statistics/ProgressBar/ProgressBarComponent.tsx
+++ b/src/components/Statistics/ProgressBar/ProgressBarComponent.tsx
@@ -1,6 +1,6 @@
 import { Divider, List, ListItem, ListItemText, Theme } from "@mui/material";
 import { makeStyles } from "@mui/styles";
-import { useState, useEffect } from "react";
+import { useState, useEffect, ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 
 import { getSemanticDomainCounts } from "backend";
@@ -16,7 +16,7 @@ const useStyles = makeStyles((theme: Theme) => ({
   },
 }));
 
-export default function ProgressBarComponent() {
+export default function ProgressBarComponent(): ReactElement {
   const { t } = useTranslation();
   const classes = useStyles();
   const [progressRatio, setProgressRatio] = useState<number>(0);
@@ -24,7 +24,7 @@ export default function ProgressBarComponent() {
   const [totalWordCount, setTotalWordCount] = useState<number>(0);
 
   useEffect(() => {
-    const updateProgress = async () => {
+    const updateProgress = async (): Promise<void> => {
       const statList = await getSemanticDomainCounts(
         LocalStorage.getProjectId(),
         defaultWritingSystem.bcp47
diff --git a/src/components/Statistics/Statistics.tsx b/src/components/Statistics/Statistics.tsx
index ccc103cf95..89f96eaa46 100644
--- a/src/components/Statistics/Statistics.tsx
+++ b/src/components/Statistics/Statistics.tsx
@@ -50,7 +50,7 @@ export default function Statistics(): ReactElement {
     getProject().then(setCurrentProject);
   }, []);
 
-  function componentToDisplay(view: viewEnum) {
+  function componentToDisplay(view: viewEnum): ReactElement {
     switch (view) {
       case viewEnum.User:
         return <DomainUserStatistics lang={lang} />;
@@ -76,7 +76,7 @@ export default function Statistics(): ReactElement {
     }
   }
 
-  function handleDisplay() {
+  function handleDisplay(): ReactElement[] {
     return [
       <Grid item key={"statistics-title"}>
         <Typography variant="h4" align="center">
@@ -94,7 +94,7 @@ export default function Statistics(): ReactElement {
     ];
   }
 
-  function handleButton() {
+  function handleButton(): ReactElement {
     return (
       <List className={classes.root}>
         <ListItemButton
diff --git a/src/components/Statistics/UserStatistics.tsx b/src/components/Statistics/UserStatistics.tsx
index 93a1ec9965..b48660ca2e 100644
--- a/src/components/Statistics/UserStatistics.tsx
+++ b/src/components/Statistics/UserStatistics.tsx
@@ -18,7 +18,7 @@ export default function UserStatistics(
   >([]);
 
   useEffect(() => {
-    const updateSemanticDomainUserCounts = async () => {
+    const updateSemanticDomainUserCounts = async (): Promise<void> => {
       const counts = await getUserStatistics(
         LocalStorage.getProjectId(),
         props.lang
diff --git a/src/components/Statistics/tests/DomainStatistics.test.tsx b/src/components/Statistics/tests/DomainStatistics.test.tsx
index ac1338bc49..c9eb90a111 100644
--- a/src/components/Statistics/tests/DomainStatistics.test.tsx
+++ b/src/components/Statistics/tests/DomainStatistics.test.tsx
@@ -1,5 +1,5 @@
 import { ListItem } from "@mui/material";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 
 import "tests/reactI18nextMock";
 
@@ -10,7 +10,7 @@ import {
   newSemanticDomainTreeNode,
 } from "types/semanticDomain";
 
-let testRenderer: renderer.ReactTestRenderer;
+let testRenderer: ReactTestRenderer;
 
 const mockProjectId = "mockProjectId";
 const mockTreeNode = newSemanticDomainTreeNode();
@@ -30,7 +30,7 @@ jest.mock("backend/localStorage", () => ({
   getProjectId: () => mockGetProjectId(),
 }));
 
-function setMockFunctions() {
+function setMockFunctions(): void {
   mockGetProjectId.mockReturnValue(mockProjectId);
   mockGetStatisticsCounts.mockResolvedValue(mockSemanticDomainCountArray);
 }
@@ -38,8 +38,8 @@ function setMockFunctions() {
 beforeEach(async () => {
   jest.clearAllMocks();
   setMockFunctions();
-  await renderer.act(async () => {
-    testRenderer = renderer.create(<DomainStatistics lang={""} />);
+  await act(async () => {
+    testRenderer = create(<DomainStatistics lang={""} />);
   });
 });
 
diff --git a/src/components/Statistics/tests/Statistics.test.tsx b/src/components/Statistics/tests/Statistics.test.tsx
index cb67e5c49b..2ac8cc43f9 100644
--- a/src/components/Statistics/tests/Statistics.test.tsx
+++ b/src/components/Statistics/tests/Statistics.test.tsx
@@ -1,5 +1,5 @@
 import { StyledEngineProvider, ThemeProvider } from "@mui/material/styles";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 
 import "tests/reactI18nextMock";
 
@@ -7,7 +7,7 @@ import Statistics from "components/Statistics/Statistics";
 import { newProject } from "types/project";
 import theme from "types/theme";
 
-let testRenderer: renderer.ReactTestRenderer;
+let testRenderer: ReactTestRenderer;
 
 const mockProject = newProject();
 const mockProjectId = "mockProjectId";
@@ -27,7 +27,7 @@ jest.mock("backend/localStorage", () => ({
   getProjectId: () => mockGetProjectId(),
 }));
 
-function setMockFunctions() {
+function setMockFunctions(): void {
   mockGetProjectId.mockReturnValue(mockProjectId);
   mockGetProject.mockResolvedValue(mockProject);
 }
@@ -35,8 +35,8 @@ function setMockFunctions() {
 beforeEach(async () => {
   jest.clearAllMocks();
   setMockFunctions();
-  await renderer.act(async () => {
-    testRenderer = renderer.create(
+  await act(async () => {
+    testRenderer = create(
       <StyledEngineProvider injectFirst>
         <ThemeProvider theme={theme}>
           <Statistics />{" "}
diff --git a/src/components/Statistics/tests/UserStatistics.test.tsx b/src/components/Statistics/tests/UserStatistics.test.tsx
index 20f4a0254d..6e1b3bd8d6 100644
--- a/src/components/Statistics/tests/UserStatistics.test.tsx
+++ b/src/components/Statistics/tests/UserStatistics.test.tsx
@@ -1,5 +1,5 @@
 import { ListItem } from "@mui/material";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 
 import "tests/reactI18nextMock";
 
@@ -7,7 +7,7 @@ import { SemanticDomainUserCount } from "api";
 import UserStatistics from "components/Statistics/UserStatistics";
 import { newSemanticDomainUserCount } from "types/semanticDomain";
 
-let testRenderer: renderer.ReactTestRenderer;
+let testRenderer: ReactTestRenderer;
 
 const mockProjectId = "mockProjectId";
 const mockSemanticDomainUserCount = newSemanticDomainUserCount();
@@ -27,7 +27,7 @@ jest.mock("backend/localStorage", () => ({
   getProjectId: () => mockGetProjectId(),
 }));
 
-function setMockFunctions() {
+function setMockFunctions(): void {
   mockGetProjectId.mockReturnValue(mockProjectId);
   mockGetDomainSenseUserStatistics.mockResolvedValue(
     mockSemanticDomainUserCountArray
@@ -37,8 +37,8 @@ function setMockFunctions() {
 beforeEach(async () => {
   jest.clearAllMocks();
   setMockFunctions();
-  await renderer.act(async () => {
-    testRenderer = renderer.create(<UserStatistics lang={""} />);
+  await act(async () => {
+    testRenderer = create(<UserStatistics lang={""} />);
   });
 });
 
diff --git a/src/components/TreeView/TreeDepiction/TreeDepictionTypes.ts b/src/components/TreeView/TreeDepiction/TreeDepictionTypes.ts
index d71b45874c..d2a7d060af 100644
--- a/src/components/TreeView/TreeDepiction/TreeDepictionTypes.ts
+++ b/src/components/TreeView/TreeDepiction/TreeDepictionTypes.ts
@@ -4,11 +4,11 @@ const MAX_COL_WIDTH = 50; // Max gap.
 const MIN_COL_WIDTH = 12; // Multiply this by RATIO_TILE_TO_GAP for min tile width.
 export const RATIO_TILE_TO_GAP = 7; // Must be odd.
 
-export function getNumCols(numChildren: number) {
+export function getNumCols(numChildren: number): number {
   return numChildren * (RATIO_TILE_TO_GAP + 1) - 1;
 }
 
-export function getColWidth(numChildren: number, totalWidth: number) {
+export function getColWidth(numChildren: number, totalWidth: number): number {
   if (!numChildren) {
     return MAX_COL_WIDTH;
   }
diff --git a/src/components/TreeView/TreeDepiction/index.tsx b/src/components/TreeView/TreeDepiction/index.tsx
index 84231fde47..f0303fbe0b 100644
--- a/src/components/TreeView/TreeDepiction/index.tsx
+++ b/src/components/TreeView/TreeDepiction/index.tsx
@@ -1,5 +1,5 @@
 import { Grid } from "@mui/material";
-import { useEffect, useState } from "react";
+import { ReactElement, useEffect, useState } from "react";
 
 import ChildrenRow from "components/TreeView/TreeDepiction/ChildrenRow";
 import CurrentRow from "components/TreeView/TreeDepiction/CurrentRow";
@@ -10,7 +10,7 @@ import {
 } from "components/TreeView/TreeDepiction/TreeDepictionTypes";
 import { useWindowSize } from "utilities/useWindowSize";
 
-export default function TreeDepiction(props: TreeDepictionProps) {
+export default function TreeDepiction(props: TreeDepictionProps): ReactElement {
   const [colWidth, setColWidth] = useState(0);
 
   const { windowWidth } = useWindowSize();
diff --git a/src/components/TreeView/TreeDepiction/tests/DomainTileButton.test.tsx b/src/components/TreeView/TreeDepiction/tests/DomainTileButton.test.tsx
index f11d7e5f25..092a3091f0 100644
--- a/src/components/TreeView/TreeDepiction/tests/DomainTileButton.test.tsx
+++ b/src/components/TreeView/TreeDepiction/tests/DomainTileButton.test.tsx
@@ -1,5 +1,5 @@
 import { Button } from "@mui/material";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 
 import "tests/reactI18nextMock";
 
@@ -7,17 +7,17 @@ import DomainTileButton from "components/TreeView/TreeDepiction/DomainTileButton
 import { Direction } from "components/TreeView/TreeDepiction/TreeDepictionTypes";
 import domMap, { mapIds } from "components/TreeView/tests/SemanticDomainMock";
 
-let tileMaster: renderer.ReactTestRenderer;
+let tileMaster: ReactTestRenderer;
 const MOCK_ANIMATE = jest.fn();
 
 describe("DomainTileButton", () => {
-  it("renders tile and matches the latest snapshot", () => {
-    createTile();
+  it("renders tile and matches the latest snapshot", async () => {
+    await createTile();
     snapTest();
   });
 
-  it("calls function on click", () => {
-    createTile();
+  it("calls function on click", async () => {
+    await createTile();
     expect(MOCK_ANIMATE).toHaveBeenCalledTimes(0);
     tileMaster.root.findByType(Button).props.onClick();
     expect(MOCK_ANIMATE).toHaveBeenCalledTimes(1);
@@ -25,9 +25,9 @@ describe("DomainTileButton", () => {
 });
 
 // Creates the tile
-function createTile(direction = Direction.Next) {
-  renderer.act(() => {
-    tileMaster = renderer.create(
+async function createTile(direction = Direction.Next): Promise<void> {
+  await act(async () => {
+    tileMaster = create(
       <DomainTileButton
         direction={direction}
         domain={domMap[mapIds.parent]}
@@ -38,6 +38,6 @@ function createTile(direction = Direction.Next) {
 }
 
 // Perform a snapshot test
-function snapTest() {
+function snapTest(): void {
   expect(tileMaster.toJSON()).toMatchSnapshot();
 }
diff --git a/src/components/TreeView/TreeDepiction/tests/index.test.tsx b/src/components/TreeView/TreeDepiction/tests/index.test.tsx
index 6a3ba83513..4013a3f339 100644
--- a/src/components/TreeView/TreeDepiction/tests/index.test.tsx
+++ b/src/components/TreeView/TreeDepiction/tests/index.test.tsx
@@ -1,4 +1,4 @@
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 
 import "tests/reactI18nextMock.ts";
 
@@ -8,7 +8,7 @@ import testDomainMap, {
   mapIds,
 } from "components/TreeView/tests/SemanticDomainMock";
 
-let treeMaster: renderer.ReactTestRenderer;
+let treeMaster: ReactTestRenderer;
 
 describe("Tests AddWords", () => {
   testFromNode("Renders correctly: from parent", testDomainMap[mapIds.parent]);
@@ -35,16 +35,16 @@ describe("Tests AddWords", () => {
 });
 
 // Perform a snapshot test
-function testFromNode(message: string, node: SemanticDomainTreeNode) {
-  it(message, () => {
-    createTree(node);
+function testFromNode(message: string, node: SemanticDomainTreeNode): void {
+  it(message, async () => {
+    await createTree(node);
     expect(treeMaster.toJSON()).toMatchSnapshot();
   });
 }
 
-function createTree(domain: SemanticDomainTreeNode) {
-  renderer.act(() => {
-    treeMaster = renderer.create(
+async function createTree(domain: SemanticDomainTreeNode): Promise<void> {
+  await act(async () => {
+    treeMaster = create(
       <TreeDepiction currentDomain={domain} animate={jest.fn()} />
     );
   });
diff --git a/src/components/TreeView/TreeSearch.tsx b/src/components/TreeView/TreeSearch.tsx
index 21f92dc1e2..9372cc1c5b 100644
--- a/src/components/TreeView/TreeSearch.tsx
+++ b/src/components/TreeView/TreeSearch.tsx
@@ -93,7 +93,9 @@ export function useTreeSearch(props: TreeSearchProps): TreeSearchState {
   }
 
   // Dispatch the search for a specified domain, and switches to it if it exists
-  async function searchAndSelectDomain(event: React.KeyboardEvent) {
+  async function searchAndSelectDomain(
+    event: React.KeyboardEvent
+  ): Promise<void> {
     event.bubbles = false;
 
     if (event.key === Key.Enter) {
@@ -117,7 +119,7 @@ export function useTreeSearch(props: TreeSearchProps): TreeSearchState {
   }
 
   // Change the input on typing
-  function handleChange(event: React.ChangeEvent<HTMLTextAreaElement>) {
+  function handleChange(event: React.ChangeEvent<HTMLTextAreaElement>): void {
     setInput(insertDecimalPoints(event.target.value));
     // Reset the error dialogue when input is changes to avoid showing an error
     // when a valid domain is entered, but Enter hasn't been pushed yet.
@@ -133,7 +135,7 @@ export function useTreeSearch(props: TreeSearchProps): TreeSearchState {
 }
 
 // Prevents keystrokes from reaching parent components; must be called onKeyDown
-function stopPropagation(event: React.KeyboardEvent) {
+function stopPropagation(event: React.KeyboardEvent): void {
   if (event.stopPropagation) {
     event.stopPropagation();
   }
diff --git a/src/components/TreeView/index.tsx b/src/components/TreeView/index.tsx
index bd96482c9e..09602f8d7f 100644
--- a/src/components/TreeView/index.tsx
+++ b/src/components/TreeView/index.tsx
@@ -66,7 +66,7 @@ export default function TreeView(props: TreeViewProps): ReactElement {
     if (!exit) {
       return;
     }
-    const handleEsc = (event: KeyboardEvent) => {
+    const handleEsc = (event: KeyboardEvent): void => {
       if (exit && event.key === Key.Escape) {
         exit();
       }
diff --git a/src/components/TreeView/tests/TreeNavigator.test.tsx b/src/components/TreeView/tests/TreeNavigator.test.tsx
index fb234eb8ba..14aadcf03d 100644
--- a/src/components/TreeView/tests/TreeNavigator.test.tsx
+++ b/src/components/TreeView/tests/TreeNavigator.test.tsx
@@ -147,7 +147,7 @@ describe("TreeNavigator", () => {
   });
 });
 
-function simulateKey(key: Key) {
+function simulateKey(key: Key): void {
   const keyDownHandler = eventListeners.get("keydown");
   expect(keyDownHandler).not.toBeUndefined();
   const simulatedArrowKey: Partial<KeyboardEvent> = { key };
diff --git a/src/components/TreeView/tests/TreeSearch.test.tsx b/src/components/TreeView/tests/TreeSearch.test.tsx
index 73e2edde19..55f6fad195 100644
--- a/src/components/TreeView/tests/TreeSearch.test.tsx
+++ b/src/components/TreeView/tests/TreeSearch.test.tsx
@@ -35,7 +35,7 @@ function getSearchInput(): HTMLInputElement {
   return screen.getByTestId(testId);
 }
 
-function setupSpies(domain: SemanticDomainTreeNode | undefined) {
+function setupSpies(domain: SemanticDomainTreeNode | undefined): void {
   jest.spyOn(backend, "getSemanticDomainTreeNode").mockResolvedValue(domain);
   jest
     .spyOn(backend, "getSemanticDomainTreeNodeByName")
@@ -44,7 +44,7 @@ function setupSpies(domain: SemanticDomainTreeNode | undefined) {
 
 describe("TreeSearch", () => {
   describe("searchAndSelectDomain", () => {
-    async function simulateTypeAndEnter(input: string) {
+    async function simulateTypeAndEnter(input: string): Promise<void> {
       // Simulate the user typing a string
       const simulatedInput = {
         target: { value: input },
diff --git a/src/components/UserSettings/AvatarUpload.tsx b/src/components/UserSettings/AvatarUpload.tsx
index f1c490da85..55f8c562e6 100644
--- a/src/components/UserSettings/AvatarUpload.tsx
+++ b/src/components/UserSettings/AvatarUpload.tsx
@@ -1,29 +1,33 @@
 import { Grid, Typography } from "@mui/material";
-import React, { useState } from "react";
+import React, { ReactElement, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import { uploadAvatar } from "backend";
 import { getUserId } from "backend/localStorage";
 import { FileInputButton, LoadingDoneButton } from "components/Buttons";
 
+interface AvatarUploadProps {
+  doneCallback?: () => void;
+}
+
 /**
  * Allows the current user to select an image and upload as their avatar
  */
-export default function AvatarUpload(props: { doneCallback?: () => void }) {
+export default function AvatarUpload(props: AvatarUploadProps): ReactElement {
   const [file, setFile] = useState<File>();
   const [filename, setFilename] = useState<string>();
   const [loading, setLoading] = useState<boolean>(false);
   const [done, setDone] = useState<boolean>(false);
   const { t } = useTranslation();
 
-  function updateFile(file: File) {
+  function updateFile(file: File): void {
     if (file) {
       setFile(file);
       setFilename(file.name);
     }
   }
 
-  async function upload(e: React.FormEvent<EventTarget>) {
+  async function upload(e: React.FormEvent<EventTarget>): Promise<void> {
     e.preventDefault();
     e.stopPropagation();
     if (file) {
@@ -34,7 +38,7 @@ export default function AvatarUpload(props: { doneCallback?: () => void }) {
     }
   }
 
-  async function onDone() {
+  async function onDone(): Promise<void> {
     setDone(true);
     if (props.doneCallback) {
       setTimeout(props.doneCallback, 500);
diff --git a/src/goals/CharacterInventory/CharInv/CharacterDetail/CharacterInfo.tsx b/src/goals/CharacterInventory/CharInv/CharacterDetail/CharacterInfo.tsx
index e484221f34..67591984d1 100644
--- a/src/goals/CharacterInventory/CharInv/CharacterDetail/CharacterInfo.tsx
+++ b/src/goals/CharacterInventory/CharInv/CharacterDetail/CharacterInfo.tsx
@@ -1,4 +1,5 @@
 import { Typography } from "@mui/material";
+import { ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 import { useSelector } from "react-redux";
 
@@ -9,7 +10,7 @@ interface CharacterInfoProps {
 }
 
 /** Displays basic information about a character */
-export default function CharacterInfo(props: CharacterInfoProps) {
+export default function CharacterInfo(props: CharacterInfoProps): ReactElement {
   const allWords = useSelector(
     (state: StoreState) => state.characterInventoryState.allWords
   );
@@ -28,12 +29,12 @@ export default function CharacterInfo(props: CharacterInfoProps) {
   );
 }
 
-function charToHexValue(char: string) {
+function charToHexValue(char: string): string {
   const hex = char.charCodeAt(0).toString(16).toUpperCase();
   return `U+${"0".repeat(4 - hex.length)}${hex}`;
 }
 
-function countCharacterOccurrences(char: string, words: string[]) {
+function countCharacterOccurrences(char: string, words: string[]): number {
   let count = 0;
   for (const word of words) {
     for (const letter of word) {
diff --git a/src/goals/CharacterInventory/CharInv/CharacterDetail/CharacterStatusControl.tsx b/src/goals/CharacterInventory/CharInv/CharacterDetail/CharacterStatusControl.tsx
index 60f2c61154..ac23103f12 100644
--- a/src/goals/CharacterInventory/CharInv/CharacterDetail/CharacterStatusControl.tsx
+++ b/src/goals/CharacterInventory/CharInv/CharacterDetail/CharacterStatusControl.tsx
@@ -1,4 +1,5 @@
 import { Button, ButtonGroup } from "@mui/material";
+import { ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 
 import { CharacterStatus } from "goals/CharacterInventory/CharacterInventoryTypes";
@@ -11,7 +12,7 @@ interface CharacterStatusControlProps {
 
 export default function CharacterStatusControl(
   props: CharacterStatusControlProps
-) {
+): ReactElement {
   const dispatch = useAppDispatch();
   const { t } = useTranslation();
 
diff --git a/src/goals/CharacterInventory/CharInv/CharacterDetail/FindAndReplace/CharacterReplaceDialog.tsx b/src/goals/CharacterInventory/CharInv/CharacterDetail/FindAndReplace/CharacterReplaceDialog.tsx
index 3bf26f6723..595f49537e 100644
--- a/src/goals/CharacterInventory/CharInv/CharacterDetail/FindAndReplace/CharacterReplaceDialog.tsx
+++ b/src/goals/CharacterInventory/CharInv/CharacterDetail/FindAndReplace/CharacterReplaceDialog.tsx
@@ -6,7 +6,7 @@ import {
   DialogContentText,
   DialogTitle,
 } from "@mui/material";
-import { useState } from "react";
+import { ReactElement, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import { LoadingButton } from "components/Buttons";
@@ -22,11 +22,13 @@ interface ReplaceDialogProps {
 /**
  * Dialog to confirm replacement
  */
-export default function CharacterReplaceDialog(props: ReplaceDialogProps) {
+export default function CharacterReplaceDialog(
+  props: ReplaceDialogProps
+): ReactElement {
   const [loading, setLoading] = useState(false);
   const { t } = useTranslation();
 
-  async function submitFindAndReplace() {
+  async function submitFindAndReplace(): Promise<void> {
     setLoading(true);
     await props.handleAccept();
     setLoading(false);
diff --git a/src/goals/CharacterInventory/CharInv/CharacterDetail/index.tsx b/src/goals/CharacterInventory/CharInv/CharacterDetail/index.tsx
index 738cfe25ae..8580c3b240 100644
--- a/src/goals/CharacterInventory/CharInv/CharacterDetail/index.tsx
+++ b/src/goals/CharacterInventory/CharInv/CharacterDetail/index.tsx
@@ -1,5 +1,6 @@
 import { Close } from "@mui/icons-material";
 import { Grid, IconButton, Typography } from "@mui/material";
+import { ReactElement } from "react";
 
 import CharacterInfo from "goals/CharacterInventory/CharInv/CharacterDetail/CharacterInfo";
 import CharacterStatusControl from "goals/CharacterInventory/CharInv/CharacterDetail/CharacterStatusControl";
@@ -13,7 +14,9 @@ interface CharacterDetailProps {
 }
 
 /** A view displaying detailed information about a character */
-export default function CharacterDetail(props: CharacterDetailProps) {
+export default function CharacterDetail(
+  props: CharacterDetailProps
+): ReactElement {
   return (
     <Grid
       container
diff --git a/src/goals/CharacterInventory/CharInv/CharacterList/CharacterCard.tsx b/src/goals/CharacterInventory/CharInv/CharacterList/CharacterCard.tsx
index e648e560a7..82b0eb1f6d 100644
--- a/src/goals/CharacterInventory/CharInv/CharacterList/CharacterCard.tsx
+++ b/src/goals/CharacterInventory/CharInv/CharacterList/CharacterCard.tsx
@@ -1,4 +1,5 @@
 import { Card, CardActionArea, CardContent, Typography } from "@mui/material";
+import { ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 
 import CharacterStatusText from "goals/CharacterInventory/CharInv/CharacterList/CharacterStatusText";
@@ -15,7 +16,7 @@ interface CharacterCardProps {
   cardWidth: number;
 }
 
-export default function CharacterCard(props: CharacterCardProps) {
+export default function CharacterCard(props: CharacterCardProps): ReactElement {
   const { t } = useTranslation();
 
   return (
diff --git a/src/goals/CharacterInventory/CharInv/CharacterList/index.tsx b/src/goals/CharacterInventory/CharInv/CharacterList/index.tsx
index f278f7e570..6cae3c7e17 100644
--- a/src/goals/CharacterInventory/CharInv/CharacterList/index.tsx
+++ b/src/goals/CharacterInventory/CharInv/CharacterList/index.tsx
@@ -1,6 +1,6 @@
 import { ArrowDownward, ArrowUpward } from "@mui/icons-material";
 import { FormControl, Grid, InputLabel, MenuItem, Select } from "@mui/material";
-import { useEffect, useState } from "react";
+import { ReactElement, useEffect, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import CharacterCard from "goals/CharacterInventory/CharInv/CharacterList/CharacterCard";
@@ -17,7 +17,7 @@ enum SortOrder {
   Status,
 }
 
-export default function CharacterList() {
+export default function CharacterList(): ReactElement {
   const cardWidth = 150;
   const fontHeight = 65;
 
diff --git a/src/goals/CharacterInventory/CharInv/index.tsx b/src/goals/CharacterInventory/CharInv/index.tsx
index 03b74bd98b..83376299a7 100644
--- a/src/goals/CharacterInventory/CharInv/index.tsx
+++ b/src/goals/CharacterInventory/CharInv/index.tsx
@@ -7,7 +7,7 @@ import {
   DialogTitle,
   Grid,
 } from "@mui/material";
-import { useEffect, useState } from "react";
+import { ReactElement, useEffect, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import { LoadingButton } from "components/Buttons";
@@ -38,7 +38,7 @@ const dialogTitleIdCancel = `${idPrefix}-cancel-dialog-title`;
 /**
  * Allows users to define a character inventory for a project
  */
-export default function CharacterInventory() {
+export default function CharacterInventory(): ReactElement {
   const dispatch = useAppDispatch();
 
   const selectedCharacter = useAppSelector(
diff --git a/src/goals/CharacterInventory/CharInv/tests/index.test.tsx b/src/goals/CharacterInventory/CharInv/tests/index.test.tsx
index 25355c8f3c..88a6106331 100644
--- a/src/goals/CharacterInventory/CharInv/tests/index.test.tsx
+++ b/src/goals/CharacterInventory/CharInv/tests/index.test.tsx
@@ -1,5 +1,5 @@
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -43,13 +43,13 @@ const mockLoadCharInvData = jest.fn();
 const mockSetSelectedCharacter = jest.fn();
 const mockUploadInventory = jest.fn();
 
-let charMaster: renderer.ReactTestRenderer;
+let charMaster: ReactTestRenderer;
 
 const mockStore = configureMockStore()({ characterInventoryState });
 
-function renderCharInvCreation() {
-  renderer.act(() => {
-    charMaster = renderer.create(
+async function renderCharInvCreation(): Promise<void> {
+  await act(async () => {
+    charMaster = create(
       <Provider store={mockStore}>
         <CharInv />
       </Provider>
@@ -57,9 +57,9 @@ function renderCharInvCreation() {
   });
 }
 
-beforeEach(() => {
+beforeEach(async () => {
   jest.resetAllMocks();
-  renderCharInvCreation();
+  await renderCharInvCreation();
 });
 
 describe("CharInv", () => {
@@ -70,30 +70,30 @@ describe("CharInv", () => {
   it("saves inventory on save", async () => {
     expect(mockUploadInventory).toHaveBeenCalledTimes(0);
     const saveButton = charMaster.root.findByProps({ id: buttonIdSave });
-    await renderer.act(async () => saveButton.props.onClick());
+    await act(async () => saveButton.props.onClick());
     expect(mockUploadInventory).toHaveBeenCalledTimes(1);
   });
 
-  it("opens a dialogue on cancel, closes on no", () => {
+  it("opens a dialogue on cancel, closes on no", async () => {
     const cancelDialog = charMaster.root.findByProps({ id: dialogIdCancel });
     expect(cancelDialog.props.open).toBeFalsy();
 
     const cancelButton = charMaster.root.findByProps({ id: buttonIdCancel });
-    renderer.act(() => cancelButton.props.onClick());
+    await act(async () => cancelButton.props.onClick());
     expect(cancelDialog.props.open).toBeTruthy();
 
     const noButton = charMaster.root.findByProps({ id: dialogButtonIdNo });
-    renderer.act(() => noButton.props.onClick());
+    await act(async () => noButton.props.onClick());
     expect(cancelDialog.props.open).toBeFalsy();
   });
 
-  it("exits on cancel-yes", () => {
+  it("exits on cancel-yes", async () => {
     const cancelButton = charMaster.root.findByProps({ id: buttonIdCancel });
-    renderer.act(() => cancelButton.props.onClick());
+    await act(async () => cancelButton.props.onClick());
     expect(mockExit).toBeCalledTimes(0);
 
     const yesButton = charMaster.root.findByProps({ id: dialogButtonIdYes });
-    renderer.act(() => yesButton.props.onClick());
+    await act(async () => yesButton.props.onClick());
     expect(mockExit).toBeCalledTimes(1);
   });
 });
diff --git a/src/goals/CharacterInventory/Redux/CharacterInventoryActions.ts b/src/goals/CharacterInventory/Redux/CharacterInventoryActions.ts
index 00f56d6103..fc75d252d6 100644
--- a/src/goals/CharacterInventory/Redux/CharacterInventoryActions.ts
+++ b/src/goals/CharacterInventory/Redux/CharacterInventoryActions.ts
@@ -184,11 +184,11 @@ export function loadCharInvData() {
 
 // Helper Functions
 
-export function exit() {
+export function exit(): void {
   router.navigate(Path.Goals);
 }
 
-function countCharacterOccurrences(char: string, words: string[]) {
+function countCharacterOccurrences(char: string, words: string[]): number {
   let count = 0;
   for (const word of words) {
     for (const letter of word) {
diff --git a/src/goals/DefaultGoal/DisplayProgress.tsx b/src/goals/DefaultGoal/DisplayProgress.tsx
index e78f4e0e3a..7ebd5e1d65 100644
--- a/src/goals/DefaultGoal/DisplayProgress.tsx
+++ b/src/goals/DefaultGoal/DisplayProgress.tsx
@@ -1,4 +1,5 @@
 import { Grid, LinearProgress, Paper, Typography } from "@mui/material";
+import { ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 import { useSelector } from "react-redux";
 
@@ -8,7 +9,7 @@ import { GoalType } from "types/goals";
 /**
  * Displays how much progress has been made in a goal
  */
-export default function DisplayProgress() {
+export default function DisplayProgress(): ReactElement | null {
   /* We cannot use a single selector for state.goalsState.currentGoal and define everything on that;
  currentStep needs its own targeted selector for it to re-render as the user progresses. */
   const currentStep = useSelector(
diff --git a/src/goals/DefaultGoal/tests/DisplayProgress.test.tsx b/src/goals/DefaultGoal/tests/DisplayProgress.test.tsx
index a1e1309d49..6dce0b2a96 100644
--- a/src/goals/DefaultGoal/tests/DisplayProgress.test.tsx
+++ b/src/goals/DefaultGoal/tests/DisplayProgress.test.tsx
@@ -1,5 +1,5 @@
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import { act, create } from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 import thunk from "redux-thunk";
 
@@ -11,16 +11,16 @@ import { Goal } from "types/goals";
 
 const createMockStore = configureMockStore([thunk]);
 let mockStore = createMockStore();
-function createMockStoreWithGoal(goal: Goal) {
+function createMockStoreWithGoal(goal: Goal): void {
   const mockStoreState = { goalsState: { currentGoal: goal } };
   mockStore = createMockStore(mockStoreState);
 }
 
 describe("DisplayProgress", () => {
-  it("Renders with default goal without crashing", () => {
+  it("Renders with default goal without crashing", async () => {
     createMockStoreWithGoal(new Goal());
-    renderer.act(() => {
-      renderer.create(
+    await act(async () => {
+      create(
         <Provider store={mockStore}>
           <DisplayProgress />
         </Provider>
@@ -28,10 +28,10 @@ describe("DisplayProgress", () => {
     });
   });
 
-  it("Renders with multi-step goal without crashing", () => {
+  it("Renders with multi-step goal without crashing", async () => {
     createMockStoreWithGoal(new MergeDups());
-    renderer.act(() => {
-      renderer.create(
+    await act(async () => {
+      create(
         <Provider store={mockStore}>
           <DisplayProgress />
         </Provider>
diff --git a/src/goals/MergeDuplicates/Redux/tests/MergeDupsDataMock.ts b/src/goals/MergeDuplicates/Redux/tests/MergeDupsDataMock.ts
index d49afbc785..c4786a8cef 100644
--- a/src/goals/MergeDuplicates/Redux/tests/MergeDupsDataMock.ts
+++ b/src/goals/MergeDuplicates/Redux/tests/MergeDupsDataMock.ts
@@ -1,7 +1,8 @@
+import { Word } from "api/models";
 import { MergeDupsData } from "goals/MergeDuplicates/MergeDupsTypes";
 import { simpleWord } from "types/word";
 
-const wordsArrayMock = () => [
+const wordsArrayMock = (): Word[] => [
   // Each simpleWord() has a randomly generated id
   simpleWord("", ""),
   simpleWord("", ""),
diff --git a/src/goals/MergeDuplicates/Redux/tests/MergeDupsReducer.test.tsx b/src/goals/MergeDuplicates/Redux/tests/MergeDupsReducer.test.tsx
index c2cef9ebf8..d0ce755111 100644
--- a/src/goals/MergeDuplicates/Redux/tests/MergeDupsReducer.test.tsx
+++ b/src/goals/MergeDuplicates/Redux/tests/MergeDupsReducer.test.tsx
@@ -93,7 +93,7 @@ describe("MergeDupReducer", () => {
   function checkTreeWords(
     action: MergeTreeAction,
     expected: Hash<MergeTreeWord>
-  ) {
+  ): void {
     const result = mergeDupStepReducer(mockState, action).tree.words;
     // We have to stringify for this test,
     // because the order of the .sensesGuids matters.
diff --git a/src/goals/MergeDuplicates/index.tsx b/src/goals/MergeDuplicates/index.tsx
index 77cdba897d..0e7b6c5385 100644
--- a/src/goals/MergeDuplicates/index.tsx
+++ b/src/goals/MergeDuplicates/index.tsx
@@ -1,3 +1,5 @@
+import { ReactElement } from "react";
+
 import MergeDupsCompleted from "goals/MergeDuplicates/MergeDupsCompleted";
 import MergeDupsStep from "goals/MergeDuplicates/MergeDupsStep";
 
@@ -5,6 +7,6 @@ interface MergeDupsProps {
   completed: boolean;
 }
 
-export default function MergeDups(props: MergeDupsProps) {
+export default function MergeDups(props: MergeDupsProps): ReactElement {
   return props.completed ? <MergeDupsCompleted /> : <MergeDupsStep />;
 }
diff --git a/src/goals/ReviewDeferredDuplicates/index.tsx b/src/goals/ReviewDeferredDuplicates/index.tsx
index 9fcdc5bb85..c04f8a5ba9 100644
--- a/src/goals/ReviewDeferredDuplicates/index.tsx
+++ b/src/goals/ReviewDeferredDuplicates/index.tsx
@@ -1,3 +1,5 @@
+import { ReactElement } from "react";
+
 import MergeDupsCompleted from "goals/MergeDuplicates/MergeDupsCompleted";
 import MergeDupsStep from "goals/MergeDuplicates/MergeDupsStep";
 
@@ -7,6 +9,6 @@ interface ReviewDeferredDupsProps {
 
 export default function ReviewDeferredDuplicates(
   props: ReviewDeferredDupsProps
-) {
+): ReactElement {
   return props.completed ? <MergeDupsCompleted /> : <MergeDupsStep />;
 }
diff --git a/src/goals/ReviewEntries/ReviewEntriesComponent/CellColumns.tsx b/src/goals/ReviewEntries/ReviewEntriesComponent/CellColumns.tsx
index 3a48802523..c61d582a7d 100644
--- a/src/goals/ReviewEntries/ReviewEntriesComponent/CellColumns.tsx
+++ b/src/goals/ReviewEntries/ReviewEntriesComponent/CellColumns.tsx
@@ -106,7 +106,7 @@ const columns: Column<any>[] = [
       return b.senses.length - a.senses.length;
     },
     editComponent: (props: FieldParameterStandard) => {
-      const deleteSense = (guid: string) => {
+      const deleteSense = (guid: string): void => {
         if (props.onRowDataChange) {
           props.onRowDataChange({
             ...props.rowData,
@@ -275,7 +275,7 @@ const columns: Column<any>[] = [
       />
     ),
     editComponent: (props: FieldParameterStandard) => {
-      const editDomains = (guid: string, domains: SemanticDomain[]) => {
+      const editDomains = (guid: string, domains: SemanticDomain[]): void => {
         if (props.onRowDataChange) {
           props.onRowDataChange({
             ...props.rowData,
diff --git a/src/goals/ReviewEntries/ReviewEntriesComponent/CellComponents/PronunciationsCell.tsx b/src/goals/ReviewEntries/ReviewEntriesComponent/CellComponents/PronunciationsCell.tsx
index 3785f9379a..4ae4d14d4a 100644
--- a/src/goals/ReviewEntries/ReviewEntriesComponent/CellComponents/PronunciationsCell.tsx
+++ b/src/goals/ReviewEntries/ReviewEntriesComponent/CellComponents/PronunciationsCell.tsx
@@ -1,3 +1,5 @@
+import { ReactElement } from "react";
+
 import PronunciationsBackend from "components/Pronunciations/PronunciationsBackend";
 import PronunciationsFrontend from "components/Pronunciations/PronunciationsFrontend";
 import {
@@ -17,11 +19,13 @@ interface PronunciationsCellProps {
   wordId: string;
 }
 
-export default function PronunciationsCell(props: PronunciationsCellProps) {
+export default function PronunciationsCell(
+  props: PronunciationsCellProps
+): ReactElement {
   const dispatch = useAppDispatch();
-  const dispatchDelete = (fileName: string) =>
+  const dispatchDelete = (fileName: string): Promise<void> =>
     dispatch(deleteAudio(props.wordId, fileName));
-  const dispatchUpload = (audioFile: File) =>
+  const dispatchUpload = (audioFile: File): Promise<void> =>
     dispatch(uploadAudio(props.wordId, audioFile));
 
   const { addNewAudio, delNewAudio, delOldAudio } = props.audioFunctions ?? {};
diff --git a/src/goals/ReviewEntries/ReviewEntriesComponent/CellComponents/tests/PronunciationsCell.test.tsx b/src/goals/ReviewEntries/ReviewEntriesComponent/CellComponents/tests/PronunciationsCell.test.tsx
index 0ad658ee89..e5cb3a1352 100644
--- a/src/goals/ReviewEntries/ReviewEntriesComponent/CellComponents/tests/PronunciationsCell.test.tsx
+++ b/src/goals/ReviewEntries/ReviewEntriesComponent/CellComponents/tests/PronunciationsCell.test.tsx
@@ -1,6 +1,6 @@
 import { ThemeProvider } from "@mui/material/styles";
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import { ReactTestRenderer, act, create } from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -47,13 +47,13 @@ const mockAudioFunctions = {
 };
 
 // Render the cell component with a store and theme
-let testRenderer: renderer.ReactTestRenderer;
+let testRenderer: ReactTestRenderer;
 const renderPronunciationsCell = async (
   pronunciationFiles: string[],
   pronunciationsNew?: string[]
-) => {
-  await renderer.act(async () => {
-    testRenderer = renderer.create(
+): Promise<void> => {
+  await act(async () => {
+    testRenderer = create(
       <ThemeProvider theme={theme}>
         <Provider store={mockStore}>
           <PronunciationsCell
@@ -85,7 +85,7 @@ describe("PronunciationsCell", () => {
 
     it("has player that dispatches action", async () => {
       await renderPronunciationsCell(["1"]);
-      await renderer.act(async () => {
+      await act(async () => {
         testRenderer.root.findByType(AudioPlayer).props.deleteAudio();
       });
       expect(mockDeleteAudio).toBeCalled();
@@ -96,7 +96,7 @@ describe("PronunciationsCell", () => {
 
     it("has recorder that dispatches action", async () => {
       await renderPronunciationsCell([]);
-      await renderer.act(async () => {
+      await act(async () => {
         testRenderer.root.findByType(AudioRecorder).props.uploadAudio();
       });
       expect(mockUploadAudio).toBeCalled();
@@ -123,7 +123,7 @@ describe("PronunciationsCell", () => {
       const playButtons = testRenderer.root.findAllByType(AudioPlayer);
 
       // player for audio present prior to row edit
-      await renderer.act(async () => {
+      await act(async () => {
         playButtons[0].props.deleteAudio();
       });
       expect(mockDelOldAudio).toBeCalled();
@@ -134,7 +134,7 @@ describe("PronunciationsCell", () => {
       jest.resetAllMocks();
 
       // player for audio added during row edit
-      await renderer.act(async () => {
+      await act(async () => {
         playButtons[1].props.deleteAudio();
       });
       expect(mockDelNewAudio).toBeCalled();
@@ -145,7 +145,7 @@ describe("PronunciationsCell", () => {
 
     it("has recorder that calls a prop function", async () => {
       await renderPronunciationsCell([], []);
-      await renderer.act(async () => {
+      await act(async () => {
         testRenderer.root.findByType(AudioRecorder).props.uploadAudio();
       });
       expect(mockAddNewAudio).toBeCalled();
diff --git a/src/goals/ReviewEntries/ReviewEntriesComponent/Redux/ReviewEntriesActions.ts b/src/goals/ReviewEntries/ReviewEntriesComponent/Redux/ReviewEntriesActions.ts
index 7fb58f09ca..63a63a645a 100644
--- a/src/goals/ReviewEntries/ReviewEntriesComponent/Redux/ReviewEntriesActions.ts
+++ b/src/goals/ReviewEntries/ReviewEntriesComponent/Redux/ReviewEntriesActions.ts
@@ -194,13 +194,19 @@ function refreshWord(
   };
 }
 
-export function deleteAudio(wordId: string, fileName: string) {
+export function deleteAudio(
+  wordId: string,
+  fileName: string
+): (dispatch: StoreStateDispatch) => Promise<void> {
   return refreshWord(wordId, (wordId: string) =>
     backend.deleteAudio(wordId, fileName)
   );
 }
 
-export function uploadAudio(wordId: string, audioFile: File) {
+export function uploadAudio(
+  wordId: string,
+  audioFile: File
+): (dispatch: StoreStateDispatch) => Promise<void> {
   return refreshWord(wordId, (wordId: string) =>
     backend.uploadAudio(wordId, audioFile)
   );
diff --git a/src/goals/ReviewEntries/ReviewEntriesComponent/ReviewEntriesTable.tsx b/src/goals/ReviewEntries/ReviewEntriesComponent/ReviewEntriesTable.tsx
index 9a6908a235..e9fa1a07cf 100644
--- a/src/goals/ReviewEntries/ReviewEntriesComponent/ReviewEntriesTable.tsx
+++ b/src/goals/ReviewEntries/ReviewEntriesComponent/ReviewEntriesTable.tsx
@@ -59,7 +59,7 @@ export default function ReviewEntriesTable(
   const [maxRows, setMaxRows] = useState(words.length);
   const [pageState, setPageState] = useState(getPageState(words.length));
 
-  const updateMaxRows = () => {
+  const updateMaxRows = (): void => {
     if (tableRef.current) {
       const tableRows = tableRef.current.state.data.length;
       if (tableRows !== maxRows) {
diff --git a/src/goals/ReviewEntries/ReviewEntriesComponent/tests/ReviewEntriesActions.test.tsx b/src/goals/ReviewEntries/ReviewEntriesComponent/tests/ReviewEntriesActions.test.tsx
index a391f8f7e1..67cda6fb0c 100644
--- a/src/goals/ReviewEntries/ReviewEntriesComponent/tests/ReviewEntriesActions.test.tsx
+++ b/src/goals/ReviewEntries/ReviewEntriesComponent/tests/ReviewEntriesActions.test.tsx
@@ -17,7 +17,7 @@ import { Bcp47Code } from "types/writingSystem";
 
 const mockGetWord = jest.fn();
 const mockUpdateWord = jest.fn();
-function mockGetWordResolve(data: Word) {
+function mockGetWordResolve(data: Word): void {
   mockGetWord.mockResolvedValue(JSON.parse(JSON.stringify(data)));
 }
 
@@ -57,7 +57,7 @@ function sense1(): Sense {
     semanticDomains: [{ ...domain1 }],
   };
 }
-function sense1_local() {
+function sense1_local(): ReviewEntriesSense {
   return new ReviewEntriesSense(sense1());
 }
 function mockFrontierWord(vernacular = "word"): Word {
@@ -93,10 +93,10 @@ describe("ReviewEntriesActions", () => {
     async function makeDispatch(
       newRevWord: ReviewEntriesWord,
       oldRevWord: ReviewEntriesWord
-    ) {
+    ): Promise<void> {
       await mockStore.dispatch<any>(updateFrontierWord(newRevWord, oldRevWord));
     }
-    function checkResultantData(newFrontierWord: Word) {
+    function checkResultantData(newFrontierWord: Word): void {
       expect(mockUpdateWord.mock.calls[0][0]).toEqual(newFrontierWord);
     }
 
diff --git a/src/goals/ReviewEntries/ReviewEntriesComponent/tests/index.test.tsx b/src/goals/ReviewEntries/ReviewEntriesComponent/tests/index.test.tsx
index 7e43ae1637..298cf1ae63 100644
--- a/src/goals/ReviewEntries/ReviewEntriesComponent/tests/index.test.tsx
+++ b/src/goals/ReviewEntries/ReviewEntriesComponent/tests/index.test.tsx
@@ -1,6 +1,6 @@
-import React from "react";
+import { Fragment } from "react";
 import { Provider } from "react-redux";
-import renderer from "react-test-renderer";
+import { act, create } from "react-test-renderer";
 import configureMockStore from "redux-mock-store";
 
 import "tests/reactI18nextMock";
@@ -70,12 +70,12 @@ const state = {
 };
 const mockStore = configureMockStore()(state);
 
-function setMockFunctions() {
+function setMockFunctions(): void {
   jest.clearAllMocks();
   mockGetFrontierWords.mockResolvedValue(
     mockReviewEntryWords.map(mockCreateWord)
   );
-  mockMaterialTable.mockReturnValue(React.Fragment);
+  mockMaterialTable.mockReturnValue(Fragment);
 }
 
 beforeEach(async () => {
@@ -87,8 +87,8 @@ beforeEach(async () => {
     }
   }
 
-  await renderer.act(async () => {
-    renderer.create(
+  await act(async () => {
+    create(
       <Provider store={mockStore}>
         <ReviewEntriesComponent />
       </Provider>
diff --git a/src/store.ts b/src/store.ts
index dfddc113db..19bf53b063 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -18,6 +18,7 @@ const immutableCheckConfig =
     ? { warnAfter: 1000 }
     : false;
 
+// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 export const setupStore = (preloadedState?: PreloadedState<RootState>) => {
   return configureStore({
     reducer: persistedReducer,
diff --git a/src/utilities/fontComponents.tsx b/src/utilities/fontComponents.tsx
index a0812f7c65..a59f8e0924 100644
--- a/src/utilities/fontComponents.tsx
+++ b/src/utilities/fontComponents.tsx
@@ -78,7 +78,7 @@ type LiWithFontProps = React.DetailedHTMLProps<
  *   `lang: string?` (bcp47 lang-tag for applying the appropriate analysis font);
  *   `vernacular: bool?` (used to apply the vernacular font).
  */
-export function LiWithFont(props: LiWithFontProps) {
+export function LiWithFont(props: LiWithFontProps): ReactElement {
   const fontContext = useContext(FontContext);
   // Use spread to remove the custom props from what is passed into li.
   const { analysis, lang, vernacular, ...liProps } = props;
diff --git a/src/utilities/fontCssUtilities.ts b/src/utilities/fontCssUtilities.ts
index 7823aed50f..85d71b7c9f 100644
--- a/src/utilities/fontCssUtilities.ts
+++ b/src/utilities/fontCssUtilities.ts
@@ -80,7 +80,7 @@ async function getFallbacks(
 }
 
 /** Given an array of font names, returns css info for them all. */
-export async function getCss(fonts: string[]) {
+export async function getCss(fonts: string[]): Promise<string[]> {
   // Get local css files when available.
   const cssDict: Hash<string> = {};
   const cssPromises = fonts.map(async (f) => {
@@ -107,7 +107,7 @@ export async function getCss(fonts: string[]) {
 }
 
 /** Given a project, returns css info for all project language fonts. */
-export async function getProjCss(proj: Project) {
+export async function getProjCss(proj: Project): Promise<string[]> {
   const fonts = proj.analysisWritingSystems.map((ws) => ws.font);
   fonts.push(proj.vernacularWritingSystem.font);
   const filtered = [...new Set(fonts.filter((f) => f))];
diff --git a/src/utilities/spellChecker.ts b/src/utilities/spellChecker.ts
index b7a5ab474e..fedada7794 100644
--- a/src/utilities/spellChecker.ts
+++ b/src/utilities/spellChecker.ts
@@ -17,7 +17,7 @@ export default class SpellChecker {
     this.updateLang(lang);
   }
 
-  async updateLang(lang?: string) {
+  async updateLang(lang?: string): Promise<void> {
     if (!lang) {
       this.bcp47 = undefined;
       return;
diff --git a/src/utilities/testUtilities.tsx b/src/utilities/testUtilities.tsx
index dde3275f03..825564203e 100644
--- a/src/utilities/testUtilities.tsx
+++ b/src/utilities/testUtilities.tsx
@@ -21,6 +21,7 @@ interface ExtendedRenderOptions extends Omit<RenderOptions, "queries"> {
   store?: AppStore;
 }
 
+// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 export function renderWithProviders(
   ui: ReactElement,
   {
diff --git a/src/utilities/tests/dictionaryLoader.test.ts b/src/utilities/tests/dictionaryLoader.test.ts
index c441d1e22c..c41d2ab6ec 100644
--- a/src/utilities/tests/dictionaryLoader.test.ts
+++ b/src/utilities/tests/dictionaryLoader.test.ts
@@ -42,7 +42,10 @@ describe("DictionaryLoader", () => {
     const mockWord0 = "foo";
     const mockWord1 = "bar";
     const mockKey1 = mockWord1.charCodeAt(0).toString();
-    const mockDict = (_lang: Bcp47Code, key?: string) =>
+    const mockDict = (
+      _lang: Bcp47Code,
+      key?: string
+    ): Promise<string | undefined> =>
       Promise.resolve(
         key === mockKey1 ? mockWord1 : key ? undefined : `1\n${mockWord0}`
       );
diff --git a/src/utilities/tests/utilities.test.ts b/src/utilities/tests/utilities.test.ts
index 3ea3f31ae7..d682457a30 100644
--- a/src/utilities/tests/utilities.test.ts
+++ b/src/utilities/tests/utilities.test.ts
@@ -2,7 +2,7 @@ import * as utilities from "utilities/utilities";
 
 describe("utilities/utilities", () => {
   describe("quicksort", () => {
-    const compareItem = (input: number) => {
+    const compareItem = (input: number): number => {
       return input;
     };
 
diff --git a/src/utilities/useWindowSize.tsx b/src/utilities/useWindowSize.tsx
index 7b22220294..41f5943605 100644
--- a/src/utilities/useWindowSize.tsx
+++ b/src/utilities/useWindowSize.tsx
@@ -4,7 +4,7 @@ export function useWindowSize(): { windowHeight: number; windowWidth: number } {
   const [windowHeight, setWindowHeight] = useState(0);
   const [windowWidth, setWindowWidth] = useState(0);
 
-  const updateWindowSize = () => {
+  const updateWindowSize = (): void => {
     // Check documentElement to account for a scrollbar.
     const { clientHeight, clientWidth } = document.documentElement;
     const { innerHeight, innerWidth } = window;