captions.coop — self-hosted live captions

Speech-to-text, a private WebSocket relay and on-server translation. Everything runs on this deployment; audio and captions are not sent to third-party services.

Start here

Everyone shares the room source.

Start captioning → Open OBS overlay

Press Start captioning and allow the microphone.
On the capture page, paste the publishing token RELAY_SOURCE_WRITE into the relay token field and tick Send caption text.
Copy the OBS overlay link into OBS as a Browser Source (enable a transparent background) and paste the viewing token RELAY_SOURCE_READ when asked.
Speech-to-text, translation and the relay all run on this server. Tokens are never placed in links.

Overlays for OBS

Overlay Standard caption display with optional text-to-speech. Enhanced overlay Adds on-server translation and context handling.

Public relay only

These pages connect to the public caption.ninja relay and cannot join the private room above.

Roll overlay — scrolling, credits-style captions.
Manual entry — type captions by hand instead of speaking.
Transcript — play a prepared script into a room.

Tools

Editor Review and republish captions. Needs the source viewing token RELAY_SOURCE_READ and the output publishing token RELAY_OUTPUT_WRITE. Translation guide How on-server translation and its languages work. vMix Titles bridge for vMix operators.

Diagnostics

Capture diagnostics Check the microphone and speech service on the Whisper host.