I built a Firefox extension that records voice notes — no server, no account, no data leaving your browser

#firefox #webextensions #privacy #javascript

Every time I had a quick thought mid-browsing, I'd stop, open a notes app, lose my train of thought, and wonder why the browser itself couldn't just record a voice memo.

So I built Voice Notes & Audio Recorder — a Firefox extension that records, plays back, and exports voice notes entirely within your browser.

What it actually does

Record voice memos — one click, no permissions dialog on repeat visits
Play back instantly — click any note to replay
Export as .webm audio — take recordings out of the browser whenever you want
Delete individually — no bulk-nuke-everything button
Completely offline — the WebRTC audio API, MediaRecorder, and localStorage, nothing else
No server, no account, no analytics — literally nowhere to send your data

The technical reality of browser audio

Firefox's MediaRecorder API makes this simpler than you'd expect. The browser asks for microphone permission once. After that, you get a MediaStream, pipe it through MediaRecorder, and collect Blob chunks.

const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
const recorder = new MediaRecorder(stream, { mimeType: 'audio/webm;codecs=opus' });
const chunks = [];
recorder.ondataavailable = e => chunks.push(e.data);
recorder.onstop = () => {
  const blob = new Blob(chunks, { type: 'audio/webm' });
  // Store locally — no upload needed
};

The recordings live in IndexedDB. The extension never makes an outbound request. You can verify this in the Firefox Network Monitor — it's completely silent.

Why "no server" is actually the right design for voice notes

Voice memos are personal. They capture thinking-out-loud, reminders, ideas that aren't ready to be text yet. They're not meant to be searchable by an AI, indexed, or tied to an account.

Browser-local storage means:

Your recordings die when you uninstall (clear the extension data)
Nothing is synced anywhere
No breach surface exists because there's nothing to breach
The extension doesn't need GDPR consent banners because there's nothing to consent to

Counterintuitive but: the lack of persistence is a feature for ephemeral voice notes.

What I didn't build (intentionally)

No cloud sync — adding a server means adding an account, auth, encryption-at-rest, GDPR obligations, and an ongoing infrastructure cost. For quick voice notes, that's overkill.
No transcription — the Web Speech API exists, but adding transcription means either sending audio to a cloud service or running a local model. Neither felt right for a first version.
No folders or tags — the most useful thing is fast capture and fast replay. Organizational features solve a different problem.

Install it

Voice Notes & Audio Recorder on Firefox Add-ons

It's free, open to inspection in AMO's review system, and the codebase is small enough to audit in an afternoon.

If you've had the same frustration — mid-browse thought, no good capture mechanism — this solves it without asking anything of you.

What other browser-local tools are missing from the Firefox extension ecosystem? I'm actively building in this space.

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