Sesame · Voice model

CSM 1B

sesame/csm-1b

Voice

Released Apr 23, 2026

CSM 1B is a conversational speech model from Sesame. It accepts text input and produces English speech output, with voice options spanning conversational and read-speech styles. At 1B parameters, it...

Specifications

Input: text, up to 20,000 characters per call
Output: mp3 (default) or raw pcm
Voice: provider voice ids via `voice`; omitted = the provider's default when it has one
Billing: per character of input text

Use it

POST /api/v1/audio/speech · MCP speak · full reference

curl https://omnirail.org/api/v1/audio/speech \
  -H "Authorization: Bearer $OMNIRAIL_KEY" -H "Content-Type: application/json" \
  -d '{"model":"sesame/csm-1b","input":"Hello from OmniRail. Every model, one key.","response_format":"mp3"}' \
  --output hello.mp3