Using Mistral for Text-to-Speech

This guide covers how to use Mistral's Text-to-Speech API with Open WebUI.

Looking for STT?

See the companion guide: Using Mistral Voxtral for Speech-to-Text

Requirements

• A Mistral API key
• Open WebUI installed and running

Quick Setup (UI)

1. Click your profile icon (bottom-left corner)
2. Select Admin Panel
3. Click Settings -> Audio tab
4. Configure the following:

Setting	Value
Text-to-Speech Engine	MistralAI
API Base URL	https://api.mistral.ai/v1
API Key	Your Mistral API key
TTS Model	voxtral-tts-26-03 (or leave empty for the built-in default)
TTS Voice	Choose from available voices

5. Click Save

Available Models

Model	Description
voxtral-tts-26-03	Voxtral TTS — current Mistral text-to-speech model, with zero-shot voice cloning

info

If AUDIO_TTS_MODEL is empty, Open WebUI falls back to mistral-tts-latest.

Set the model explicitly

Mistral no longer publishes -latest alias names, so the built-in mistral-tts-latest fallback may be rejected. Set TTS Model to a current ID such as voxtral-tts-26-03 rather than leaving the field empty. See the Mistral models overview for the current list.

Environment Variables Setup

If you prefer to configure via environment variables:

services:
  open-webui:
    image: ghcr.io/open-webui/open-webui:main
    environment:
      - AUDIO_TTS_ENGINE=mistral
      - AUDIO_TTS_MISTRAL_API_KEY=your-mistral-api-key
      - AUDIO_TTS_MISTRAL_API_BASE_URL=https://api.mistral.ai/v1
      - AUDIO_TTS_MODEL=voxtral-tts-26-03
      - AUDIO_TTS_VOICE=<voice-id>
    # ... other configuration

All Mistral TTS Environment Variables

Variable	Description	Default
AUDIO_TTS_ENGINE	Set to mistral	empty (uses browser-only TTS)
AUDIO_TTS_MISTRAL_API_KEY	Your Mistral API key	empty
AUDIO_TTS_MISTRAL_API_BASE_URL	Mistral API base URL	https://api.mistral.ai/v1
AUDIO_TTS_MODEL	TTS model	mistral-tts-latest (built-in fallback; set voxtral-tts-26-03 explicitly)
AUDIO_TTS_VOICE	Voice ID	empty

Choosing Voices

Open WebUI queries the configured Mistral endpoint for available voices and shows them in the TTS Voice selector.

If voices are not listed:

• Confirm your API key is valid
• Verify the API base URL is reachable from the Open WebUI server/container
• Check logs for /audio/voices request errors

Testing TTS

1. Start a new chat
2. Send a message to any model
3. Click the speaker icon on the AI response to hear it read aloud

Troubleshooting

"Mistral API key is required for Mistral TTS"

1. Confirm AUDIO_TTS_MISTRAL_API_KEY is set (or entered in Admin Audio settings)
2. Save settings and retry

No voices shown in the dropdown

1. Verify network access from Open WebUI to AUDIO_TTS_MISTRAL_API_BASE_URL
2. Check Open WebUI logs for Mistral voice list errors
3. Confirm your key has permission to access Mistral audio APIs

TTS request fails

1. Verify AUDIO_TTS_ENGINE=mistral
2. Set the model explicitly to a current ID such as voxtral-tts-26-03
3. Try another voice ID from the fetched list

For broader audio debugging, see the Audio Troubleshooting Guide.