diff --git a/route/export.js b/route/export.js
index f998e42..3bdda7f 100644
--- a/route/export.js
+++ b/route/export.js
@@ -803,83 +803,140 @@ const addExtensionFromMime = (name, mime) => {
     return `${name}.${getExtension(mime)}`
 }
 
-const archiverAppendDbImage = (archiver, db, imageId, name) => {
-    return db.collection('image').findOne({ _id: imageId }).then(
-        image => image
-            ? archiver.append(image.buffer.buffer, { name: addExtensionFromMime(name, image.mime), date: image.created })
-            : null
+// `generateFn` is provided with the following object to
+// maintain backpressure:
+//
+// {
+//    shouldStop(): returns whether the stream is ended
+//       (e.g. when client connection is lost). generateFn
+//       should exit after this returns true.
+//
+//    append(): same as archiver's append(), except it
+//       returns after the entry has been processed
+//
+//    finalize(): same as archiver's finalize()
+// }
+function streamZipArchive(generateFn) {
+    const archiver = Archiver('zip', {store: true})
+    const outStream = archiver.pipe(new PassThrough())
+
+    // Defer the following execution after we return, so Koa can start
+    // streaming the response instead of holding it in memory
+    ;(async function() {
+        let streamEnded = false
+        outStream.once('close', () => streamEnded = true)
+
+        generateFn({
+            shouldStop() { return streamEnded },
+            append(...args) {
+                archiver.append(...args)
+                return new Promise(resolve => archiver.once('entry', resolve))
+            },
+            finalize() { return archiver.finalize() }
+        })
+    })()
+
+    return outStream
+}
+
+const appendDbImageToZipStream = async (zipStream, db, imageId, name) => {
+    const image = await db.collection('image').findOne({ _id: imageId })
+
+    if (!image)
+        return
+
+    return zipStream.append(
+        image.buffer.buffer,
+        { name: addExtensionFromMime(name, image.mime), date: image.created }
     )
 }
 
 route.get('/export/committees/photos',
     TokenAccessFilter(AccessFilter('finance', 'admin')),
     async ctx => {
-        let archiver = Archiver('zip', {store: true})
         ctx.status = 200
         ctx.set('content-type', 'application/zip;charset=utf-8')
-        ctx.body = archiver.pipe(new PassThrough())
-        const committees = await ctx.db.collection('committee').aggregate(LOOKUP_COMMITTEE).toArray()
-        const createName = NameCreator()
-        for (let committee of committees) {
-            const name = createName(GV(committee, 'role') + '-' + GV(committee, 'contact.name'))
-            await archiverAppendDbImage(archiver, ctx.db, committee.photoId, name)
-        }
-        archiver.finalize()
+        ctx.body = streamZipArchive(async (zipStream) => {
+            const committees = await ctx.db.collection('committee').aggregate(LOOKUP_COMMITTEE).toArray()
+            const createName = NameCreator()
+            for (let committee of committees) {
+                if (zipStream.shouldStop())
+                    break
+
+                const name = createName(GV(committee, 'role') + '-' + GV(committee, 'contact.name'))
+                await appendDbImageToZipStream(zipStream, ctx.db, committee.photoId, name)
+            }
+            zipStream.finalize()
+        })
     }
 )
 
 route.get('/export/daises/photos',
     TokenAccessFilter(AccessFilter('finance', 'admin')),
     async ctx => {
-        let archiver = Archiver('zip', {store: true})
         ctx.status = 200
         ctx.set('content-type', 'application/zip;charset=utf-8')
-        ctx.body = archiver.pipe(new PassThrough())
-        const daises = await ctx.db.collection('dais').aggregate(LOOKUP_DAIS).toArray()
-        const createName = NameCreator()
-        for (let dais of daises) {
-            const name = createName(GV(dais, 'role') + '-' + GV(dais, 'contact.name'))
-            await archiverAppendDbImage(archiver, ctx.db, dais.photoId, name)
-        }
-        archiver.finalize()
+        ctx.body = streamZipArchive(async (zipStream) => {
+            const daises = await ctx.db.collection('dais').aggregate(LOOKUP_DAIS).toArray()
+            const createName = NameCreator()
+            for (let dais of daises) {
+                if (zipStream.shouldStop())
+                    break
+
+                const name = createName(GV(dais, 'role') + '-' + GV(dais, 'contact.name'))
+                await appendDbImageToZipStream(zipStream, ctx.db, dais.photoId, name)
+            }
+            zipStream.finalize()
+        })
     }
 )
 
 route.get('/export/representatives/photos',
     TokenAccessFilter(AccessFilter('finance', 'admin')),
     async ctx => {
-        let archiver = Archiver('zip', {store: true})
         ctx.status = 200
         ctx.set('content-type', 'application/zip;charset=utf-8')
-        ctx.body = archiver.pipe(new PassThrough())
-        const representatives = await ctx.db.collection('representative').aggregate(LOOKUP_REPRESENTATIVE, AGGREGATE_OPTS).toArray()
-        const createName = NameCreator()
-        for (let representative of representatives) {
-            const name = createName(GV(representative, 'school.school.name') + '-' + GV(representative, 'contact.name') + '-' + GV(representative, 'identification.number'))
-            await archiverAppendDbImage(archiver, ctx.db, representative.avatar_image, name)
-        }
-        archiver.finalize()
+        ctx.body = streamZipArchive(async (zipStream) => {
+            const representatives = await ctx.db.collection('representative').aggregate(LOOKUP_REPRESENTATIVE, AGGREGATE_OPTS).toArray()
+            const createName = NameCreator()
+            for (let representative of representatives) {
+                if (zipStream.shouldStop())
+                    break
+
+                const name = createName(GV(representative, 'school.school.name') + '-' + GV(representative, 'contact.name') + '-' + GV(representative, 'identification.number'))
+                await appendDbImageToZipStream(zipStream, ctx.db, representative.avatar_image, name)
+            }
+            zipStream.finalize()
+        })
     }
 )
 
 route.get('/export/representatives/disclaimers',
     TokenAccessFilter(AccessFilter('finance', 'admin')),
     async ctx => {
-        let archiver = Archiver('zip', {store: true})
         ctx.status = 200
         ctx.set('content-type', 'application/zip;charset=utf-8')
-        ctx.body = archiver.pipe(new PassThrough())
-        const representatives = await ctx.db.collection('representative').aggregate(LOOKUP_REPRESENTATIVE, AGGREGATE_OPTS).toArray()
-        const createName = NameCreator()
-        for (let representative of representatives) {
-            const name = createName(
-                  GV(representative, 'school.school.name') + '-'
-                + (GV(representative, 'contact.name') || GV(representative, '_id')) + '-'
-                + GV(representative, 'identification.number')
-            )
-            await archiverAppendDbImage(archiver, ctx.db, representative.disclaimer_image, name)
-        }
-        archiver.finalize()
+        ctx.body = streamZipArchive(async (zipStream) => {
+            const representatives = await ctx.db.collection('representative')
+                .aggregate(LOOKUP_REPRESENTATIVE, AGGREGATE_OPTS)
+                .toArray()
+            const createName = NameCreator()
+
+            for (let representative of representatives) {
+                if (zipStream.shouldStop())
+                    break
+
+                const name = createName(
+                    GV(representative, 'school.school.name') + '-'
+                    + (GV(representative, 'contact.name') || GV(representative, '_id')) + '-'
+                    + GV(representative, 'identification.number')
+                )
+
+                await appendDbImageToZipStream(zipStream, ctx.db, representative.disclaimer_image, name)
+            }
+
+            zipStream.finalize()
+        })
     }
 )
 
@@ -899,30 +956,30 @@ route.get('/export/daises/reimbursements',
 route.get('/export/daises/reimbursement-credentials',
     TokenAccessFilter(AccessFilter('finance', 'admin')),
     async ctx => {
-        const STATES_TO_EXPORT = ['approved', 'completed']
-        let archiver = Archiver('zip', {store: true})
         ctx.status = 200
         ctx.set('content-type', 'application/zip;charset=utf-8')
-        ctx.body = archiver.pipe(new PassThrough())
-        const daises = await ctx.db.collection('dais').aggregate(LOOKUP_DAIS_REIMBURSEMENT, AGGREGATE_OPTS).toArray()
-        const createName = NameCreator()
-        for (let dais of daises) {
-            const inboundState = GV(dais, 'reimbursement.inbound.state')
-            if (STATES_TO_EXPORT.includes(inboundState)) {
-                const inboundCreds = GV(dais, 'reimbursement.inbound.credential') || []
-                const name = createName(GV(dais, 'contact.name') + '-来程')
-                for (let photoId of inboundCreds)
-                    await archiverAppendDbImage(archiver, ctx.db, photoId, name)
-            }
-            const outboundState = GV(dais, 'reimbursement.outbound.state')
-            if (STATES_TO_EXPORT.includes(outboundState)) {
-                const outboundCreds = GV(dais, 'reimbursement.outbound.credential') || []
-                const name = createName(GV(dais, 'contact.name') + '-回程')
-                for (let photoId of outboundCreds)
-                    await archiverAppendDbImage(archiver, ctx.db, photoId, name)
+        ctx.body = streamZipArchive(async (zipStream) => {
+            const STATES_TO_EXPORT = ['approved', 'completed']
+            const daises = await ctx.db.collection('dais').aggregate(LOOKUP_DAIS_REIMBURSEMENT, AGGREGATE_OPTS).toArray()
+            const createName = NameCreator()
+            for (let dais of daises) {
+                const inboundState = GV(dais, 'reimbursement.inbound.state')
+                if (STATES_TO_EXPORT.includes(inboundState)) {
+                    const inboundCreds = GV(dais, 'reimbursement.inbound.credential') || []
+                    const name = createName(GV(dais, 'contact.name') + '-来程')
+                    for (let photoId of inboundCreds)
+                        await appendDbImageToZipStream(zipStream, ctx.db, photoId, name)
+                }
+                const outboundState = GV(dais, 'reimbursement.outbound.state')
+                if (STATES_TO_EXPORT.includes(outboundState)) {
+                    const outboundCreds = GV(dais, 'reimbursement.outbound.credential') || []
+                    const name = createName(GV(dais, 'contact.name') + '-回程')
+                    for (let photoId of outboundCreds)
+                        await appendDbImageToZipStream(zipStream, ctx.db, photoId, name)
+                }
             }
-        }
-        archiver.finalize()
+            zipStream.finalize()
+        })
     }
 )