diff --git a/gax/.jsdoc.cjs b/gax/.jsdoc.cjs
deleted file mode 100644
index 3c0a8210b..000000000
--- a/gax/.jsdoc.cjs
+++ /dev/null
@@ -1,52 +0,0 @@
-// Copyright 2019 Google LLC
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-
-'use strict';
-
-module.exports = {
-  opts: {
-    readme: '../README.md',
-    package: './package.json',
-    template: './node_modules/jsdoc-fresh',
-    recurse: true,
-    verbose: true,
-    destination: './docs/'
-  },
-  plugins: [
-    'plugins/markdown',
-    'jsdoc-region-tag'
-  ],
-  source: {
-    excludePattern: '(^|\\/|\\\\)[._]',
-    include: [
-      'build/src',
-      'build/protos'
-    ],
-    includePattern: '\\.js$'
-  },
-  templates: {
-    copyright: 'Copyright 2024 Google, LLC.',
-    includeDate: false,
-    sourceFiles: false,
-    systemName: 'google-gax',
-    theme: 'lumen',
-    default: {
-      outputSourceFiles: false
-    }
-  },
-  markdown: {
-    idInHeadings: true
-  }
-};
diff --git a/gax/.jsdoc.json b/gax/.jsdoc.json
new file mode 100644
index 000000000..a2c796518
--- /dev/null
+++ b/gax/.jsdoc.json
@@ -0,0 +1,35 @@
+{
+  "opts": {
+    "readme": "../README.md",
+    "package": "./package.json",
+    "template": "./node_modules/jsdoc-fresh",
+    "recurse": true,
+    "verbose": true,
+    "destination": "./docs/"
+  },
+  "plugins": [
+    "plugins/markdown",
+    "jsdoc-region-tag"
+  ],
+  "source": {
+    "excludePattern": "(^|\\/|\\\\)[._]",
+    "include": [
+      "build/esm/src",
+      "build/protos"
+    ],
+    "includePattern": "\\.js$"
+  },
+  "templates": {
+    "copyright": "Copyright 2024 Google, LLC.",
+    "includeDate": false,
+    "sourceFiles": false,
+    "systemName": "google-gax",
+    "theme": "lumen",
+    "default": {
+      "outputSourceFiles": false
+    }
+  },
+  "markdown": {
+    "idInHeadings": true
+  }
+}
diff --git a/gax/esm/test/showcase-echo-client/.babelrc b/gax/esm/test/showcase-echo-client/.babelrc
new file mode 100644
index 000000000..d2253052f
--- /dev/null
+++ b/gax/esm/test/showcase-echo-client/.babelrc
@@ -0,0 +1,19 @@
+{
+    "presets": [
+      "@babel/preset-typescript",
+      "@babel/env"
+    ],
+    "plugins": [
+      [
+        "replace-import-extension",
+        {
+          "extMapping": {
+            ".js": ".cjs"
+          }
+        }
+      ],
+      "./node_modules/gapic-tools/build/src/replaceESMMockingLib.js",
+      "./node_modules/gapic-tools/build/src/replaceImportMetaUrl.js",
+      "./node_modules/gapic-tools/build/src/toggleESMFlagVariable.js"
+    ]
+  }
\ No newline at end of file
diff --git a/gax/package.json b/gax/package.json
index cd2cc5f4a..1d0e23698 100644
--- a/gax/package.json
+++ b/gax/package.json
@@ -36,12 +36,23 @@
         "types": "./build/cjs/src/protobuf.d.ts",
         "default": "./build/cjs/src/protobuf.cjs"
       }
+    },
+    "./build/src/protobuf.js": {
+      "import": {
+        "types": "./build/esm/src/protobuf.d.ts",
+        "default": "./build/esm/src/protobuf.js"
+      },
+      "require": {
+        "types": "./build/cjs/src/protobuf.d.ts",
+        "default": "./build/cjs/src/protobuf.cjs"
+      }
     }
   },
   "dependencies": {
     "@grpc/grpc-js": "^1.10.9",
     "@grpc/proto-loader": "^0.7.13",
     "@types/long": "^4.0.0",
+    "@types/duplexify": "^3.6.4",
     "abort-controller": "^3.0.0",
     "duplexify": "^4.0.0",
     "google-auth-library": "^9.3.0",
@@ -58,7 +69,6 @@
     "@babel/plugin-proposal-private-methods": "^7.18.6",
     "@babel/preset-env": "^7.26.0",
     "@babel/preset-typescript": "^7.26.0",
-    "@types/duplexify": "^3.6.4",
     "@types/mocha": "^9.0.0",
     "@types/ncp": "^2.0.1",
     "@types/node": "^20.5.0",
@@ -83,7 +93,7 @@
     "jsdoc": "^4.0.0",
     "jsdoc-fresh": "^3.0.0",
     "jsdoc-region-tag": "^3.0.0",
-    "linkinator": "^4.0.0",
+    "linkinator": "^6.0.0",
     "long": "^4.0.0",
     "lru-cache": "10.4.3",
     "mkdirp": "^2.0.0",
@@ -104,7 +114,7 @@
     "webpack-cli": "^4.0.0"
   },
   "scripts": {
-    "docs": "jsdoc -c .jsdoc.js",
+    "docs": "jsdoc -c .jsdoc.json",
     "pretest": "npm run prepare",
     "test:cjs": "mocha build/cjs/test/unit",
     "test:esm": "mocha build/esm/test/unit --loader=esmock --enable-source-maps",