Firefox users · Browser-agnostic
OBS Caption Tool That Works on Firefox
Firefox does not have free browser-native speech recognition, so most free caption tools fail there. StreamTranslate uses Deepgram server-side speech recognition — works in Firefox, Safari, Chrome, and Edge identically.
No credit card. 6-hour free trial. Works on any browser.
TL;DR
Firefox does not implement the Web Speech API that Caption.Ninja, Web Captioner, and similar free tools depend on. StreamTranslate runs speech recognition server-side via Deepgram, so it works in every browser. 6-hour free trial.
Why Firefox is locked out of most caption tools
Free OBS caption tools (Caption.Ninja, the shut-down Web Captioner, Zip Captions) use Chrome's Web Speech API for speech recognition. Firefox does not implement that API for free server-side speech-to-text. So those tools simply do not work in Firefox.
Mozilla has Bergamot (which Caption.Ninja uses for free translation), but Bergamot is just translation, not speech recognition. Mozilla does not provide free speech-to-text. Firefox users who try to use these tools see no transcription happening.
StreamTranslate works in Firefox identically to Chrome
Our architecture does not care which browser you use. We capture mic audio via the standard MediaRecorder API (which Firefox fully supports), stream it to our servers, run Deepgram Nova-3 speech recognition, send back transcription + translation.
Firefox, Chrome, Safari, Edge — same setup, same workflow, same result.
Setup in Firefox
- Open streamtranslate.live/control in Firefox.
- Allow microphone access.
- Choose spoken + target language.
- Copy the OBS browser source URL.
- OBS → Sources → + → Browser → paste → 1920x1080. Go live.
Frequently asked questions
Does Caption.Ninja work in Firefox?
Partially. The overlay page can display captions, but the speech recognition page (where captions are generated) does not work because Firefox lacks the Web Speech API.
Why does Firefox not have free speech recognition?
Mozilla chose not to ship browser-native speech recognition tied to a backend service. They focus on translation (Bergamot) and other features. Firefox users who need speech recognition rely on third-party paid APIs.
Does StreamTranslate use Firefox features that might break?
No. We use widely-supported APIs (MediaRecorder, WebSocket) that Firefox has supported since 2014.
What if Firefox releases a Web Speech API in the future?
Would not affect us either way — we already have professional speech recognition via Deepgram. We do not depend on browsers shipping speech models.