Your audio never leaves the device.

Murmur is a single-binary Mac app. There is no Murmur server. The only outside service it ever calls is Claude's API, and only when you opt in to AI mode with screen context.

Audio

Whisper runs locally on your Mac via Apple's MLX framework. There is no streaming, no audio upload, and no cloud transcription option. Both quick mode and AI mode transcribe on-device.

While you hold the hotkey, Murmur captures microphone input into an in-memory buffer. Nothing is written to disk. On release, Whisper transcribes the buffer locally and the buffer is freed.

Screen context

Off by default. You enable it in the setup wizard, and it only fires when you trigger AI mode (double-tap, then hold). Quick-mode dictation never captures the screen.

When AI mode runs with screen context on, Murmur captures one PNG of the focused window, base64-encodes it, sends it to api.anthropic.com alongside the transcript and your customisable prompt, and discards it on receipt. Screenshots are never written to disk.

If you turn screen context off in the wizard, AI mode still works. Claude just gets the transcript and prompt without an image.

Replies (AI mode only)

Claude generates the polished reply and returns it. Murmur pastes it into the focused field and forgets it. We don't log or store replies.

Claude API terms (commercial terms govern what they do with the request. By default API traffic is not used to train models. Quick mode never calls Claude at all.

API keys

Your Claude API key is stored locally in ~/.config/voice-reply/config.json, readable only by your user account. Murmur reads it only when making an AI mode request.

Murmur has no backend, no analytics, and no telemetry. There is nowhere else for the key (or anything else) to go.

What Murmur never does

• Record audio when you're not holding the hotkey.
• Take screenshots in quick mode, or in AI mode when screen context is off.
• Send transcripts anywhere in quick mode. No network call at all.
• Send anything to a Murmur-owned server. There isn't one.
• Phone home for analytics, crash reports, or update checks unless you explicitly opt in.

Questions

If anything here is unclear or you want detail on a specific code path, the source is open. Read it, or email hello@murmur.app.