Gemini TTS Downloader

Download Google Gemini's "Listen" TTS audio responses as files.
No waiting through playback. No menu hunting. One click, file in Downloads.

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What it does

Gemini's Listen feature is buried behind a 3-dot menu, and there's no built-in way to keep a copy of the audio without sitting through real-time playback. This Chrome extension fixes both:

• Adds a Download option right inside the 3-dot menu, next to Listen
• Pulls the audio directly out of Gemini's blob URL — typically saves in 2-3 seconds regardless of how long the clip would take to play
• Saves silently — no audio plays during capture
• Names files <conversation-title>-<message-index>.mp3 so they're sortable

Demo

Drop a GIF or screenshot here once you record one.

   ┌──────────────────────────────┐
   │  [3-dot menu opens]          │
   │  ─────────────────────       │
   │  🔊 Listen                   │
   │  ⬇️  Download   ← injected   │
   │  📋 Copy                     │
   │  ⋮                           │
   └──────────────────────────────┘

Install (developer / unpacked)

The extension is not (yet) on the Chrome Web Store. To install from source:

1. Clone this repo

   git clone https://github.com/zachisparanoid/GeminiTTS-Download.git
   cd GeminiTTS-Download

2. Open chrome://extensions in Chrome
3. Toggle Developer mode on (top-right)
4. Click Load unpacked
5. Select the extension/ directory inside this repo
6. Visit https://gemini.google.com/, hover over an assistant message, open the 3-dot menu — Download sits right next to Listen

For more detail, see extension/README.md.

How it works

┌─────────────────────────────────────────────────────────────┐
│                       gemini.google.com                     │
│                                                             │
│   ┌─────────────────┐    postMessage    ┌─────────────────┐ │
│   │ content script  │ ◄──────────────► │ page-world script│ │
│   │ (isolated world)│                   │   (main world)   │ │
│   └────────┬────────┘                   └────────┬─────────┘ │
│            │                                     │           │
│   - injects "Download"             - patches URL.createObjectURL
│   - tracks 3-dot clicks            - patches HTMLMediaElement.play
│   - builds Blob locally            - mutes/pauses audio
│   - triggers <a download>          - posts captured bytes back
└─────────────────────────────────────────────────────────────┘

1. The content script watches Gemini's DOM and injects a Download item into the per-message 3-dot menu.
2. The page-world script monkey-patches URL.createObjectURL. The moment Gemini constructs a Blob for a TTS response, we read its bytes via blob.arrayBuffer() — no waiting for playback to finish.
3. While capture is in flight, HTMLMediaElement.prototype.play is short-circuited so no audio actually plays.
4. The bytes are passed back to the content script (via window.postMessage with a transferable ArrayBuffer), wrapped in a Blob, and triggered as a download via a hidden <a download> anchor click.

For implementation details, the source files are heavily commented — start with extension/content-script.js and extension/injected.js.

Built with

• Vanilla JavaScript, no bundler, no transpiler, no dependencies
• Manifest V3, content scripts only (no service worker — capture and save both happen in-page)
• Filename module unit tests via Node's built-in node:test

Run tests

cd extension
npm test

Permissions

• host_permissions: https://gemini.google.com/* — that's it.

No downloads, no tabs, no storage, no notifications. The download itself is triggered via a hidden <a download> element click, so no privileged API is required. No telemetry, no remote calls, no data leaving your machine.

Limitations / known caveats

• Gemini's DOM selectors are best-effort. If Google ships a redesign, the menu-injection selectors may need tweaks. They all live in one SELECTORS object at the top of extension/content-script.js.
• The capture path assumes Gemini delivers TTS via a blob: URL on an <audio> element. If that ever changes, the existing fetch interception is a fallback path.
• A 30-second timeout is enforced — if no audio response arrives within that window, the download is abandoned with a toast error.

Contributing

Issues and PRs welcome. The codebase is small (≈700 lines of JS total) and source files are commented to explain architectural choices.

If a Gemini DOM change breaks the extension, the fix is usually one regex in the SELECTORS object at the top of extension/content-script.js — please open a PR.

License

MIT — © 2026 Zachary Winchester

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