Recognition that never leaves your Mac

For the calls you would rather not send anywhere, Subtl can run speech recognition locally. The audio is processed on your machine and nothing about it is transmitted.

Download for macOS — free

What local actually means

With local recognition on, the audio goes from the call to a Whisper model running inside Subtl, and the text stays on your Mac. Nothing is sent to us or to any provider.

Translation and the answer suggestions are separate steps that use a cloud model — they receive a sentence of text, not audio. Switch both off and keep the transcript, and the call leaves your device in no form at all.

Which Macs are fast enough?

Apple silicon with 16 GB of memory runs it comfortably. Machines with 8 GB, and Intel Macs, can run it but fall behind a fast speaker — which matters more for live reading than for a transcript you review afterwards.

What you give up

On clear speech, accuracy is close to the cloud model. On crosstalk, heavy accents and specialised vocabulary the cloud model is still better. The model is a one-time download of about 1 GB, and after that it works with no network.

Switching it on

Settings → AI → Speech recognition has three options: Auto, Cloud and On this device. Auto chooses for you and says on the start screen which it picked and why.

The middle option: your own API key

If the concern is whose account the cloud call runs on rather than the cloud itself, the Pro plan with your own key costs $14 a month. The key stays in the macOS keychain, and our credits are never used on that plan.

Questions

Is the Whisper model included?

It downloads inside the app the first time you choose on-device recognition — one click, about 1 GB. Nothing else to install.

Does local mode work offline?

Recognition does. Translation and answer suggestions need a connection; the transcript works without one.

Is this the same as the privacy of the cloud mode?

In the cloud mode audio is sent over TLS to the recognition provider and not stored by us. In local mode it is not sent at all. The difference is where it is processed, not whether it is kept.