As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/m/sesame-csm-1b/

# Sesame CSM-1B (Conversational Speech Model)

Sesame, CSM family. Status: current. Type: speech and audio. Released: 2025-03-13.

## How to call it

| Provider | Model id | Endpoint | Docs |
|---|---|---|---|
| Hugging Face | `sesame/csm-1b` |  | https://huggingface.co/sesame/csm-1b |
| Transformers | `sesame/csm-1b` |  | https://huggingface.co/docs/transformers/model_doc/csm |
| Sesame app (Maya, Miles, Simone, Charlie — hosted larger models) |  |  | https://www.sesame.com/ |

## Pricing

- Price not published.
- Last checked: 2026-09-29

## Specs

- Input: text, audio
- Output: audio
- Context window: not published
- Max output: not published
- Open weights: yes
- Licence: apache-2.0

## Where it stands

- Newer speech and audio models in the registry since its release: 100. The 5 newest:
  - NVIDIA Nemotron 3.5 Transcribe (30B-A4B) (2026-10-28) https://postcutoff.com/m/nemotron-3-5-transcribe/
  - Hy-SimulMT-30B-A3B (2026-10-22) https://postcutoff.com/m/hy-simulmt-30b-a3b/
  - Eleven Realtime v1 Max / Mini (2026-10-20) https://postcutoff.com/m/eleven-realtime-v1-max/
  - Voxtral Mini Transcribe 3 (+ Mini Transcribe Realtime 3) (2026-10-20) https://postcutoff.com/m/voxtral-mini-transcribe-3/
  - Voxtral Small Transcribe 3 (2026-10-20) https://postcutoff.com/m/voxtral-small-transcribe-3/
- Weights are public under a permissive licence (Apache-2.0).

## What stands out

- Context-conditioned conversational TTS: Llama backbone + audio decoder emitting Mimi audio codes; generates speech conditioned on prior conversation audio/text so prosody fits the dialogue; voice prompting via context segments. Source: https://huggingface.co/sesame/csm-1b

## Notes

Open base generation model only (no fine-tuned voices, English-centric, cannot generate text itself); the Maya/Miles demo voices use Sesame's larger in-house models. Native in Transformers since v4.52.1. Sesame raised a $250M Series B (Oct 2025, Sequoia/Spark) and launched a public-preview iOS app with four agents (Maya, Miles, Simone, Charlie) in 39 countries on 2026-05-28; smart glasses targeted for 2027. No newer open Sesame model found as of 2026-09-29.

Sources: https://huggingface.co/sesame/csm-1b , https://techcrunch.com/2026/05/28/sesame-the-conversational-ai-startup-from-oculus-founders-launches-its-ios-app/

Model page: https://postcutoff.com/m/sesame-csm-1b/