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Speech to Text

Libre WebUI can transcribe microphone recordings through an active plugin that declares a speech-to-text capability. When the browser exposes its speech recognition service, Chat selects that service by default; its implementation and data handling are controlled by the browser vendor and are not necessarily on-device. Select a named provider explicitly to use provider-backed STT. When the browser service is unavailable, Chat selects the first compatible provider.

Bundled support includes:

  • OpenAI transcription models through a multipart /v1/audio/transcriptions request; and
  • Hugging Face automatic speech recognition models through its raw-audio inference endpoint.

The browser records only after the user presses the microphone button. Chat shows the selected provider and transfer notice before recording. Press the button again to stop recording; while transcription is running, the same button cancels the provider request. Libre inserts the returned transcript into the composer. The recording is held in memory for the request and is not saved by Libre WebUI. Navigating to another chat cancels pending microphone permission, recording, and transcription work.

Provider contract​

An STT capability declares an endpoint, model map, accepted formats, request mode, and optional endpoint variable. Libre validates the authenticated user's exact plugin/model route before forwarding audio. Libre currently accepts uncompressed PCM WAV and Opus WebM recordings. It validates the filename extension, declared MIME type, container structure, codec identifier, sample rate, channels, decoded-size ratio, and duration before forwarding audio. Requests are limited to 25 MiB and 300 seconds globally (or a lower manifest limit), bounded to two concurrent transcriptions per user and six across the deployment, and aborted when the browser disconnects or the renewable shared admission permit is lost. Redis admission failure in team mode fails closed; it never creates an independent per-replica allowance.

Provider credentials remain on the backend. Libre refuses redirects so an authorization header or audio recording cannot be forwarded to a different host. Provider authentication failures are surfaced as an upstream failure, not as an expired Libre session.

Use HTTPS for the Libre WebUI origin and remote providers. Browsers do not expose microphone capture to an insecure remote origin, and Libre does not advertise either speech path unless the browser exposes its secure-origin media APIs. The provider may retain or process recordings under its own terms, so review that policy before dictating sensitive text.