Both add live captions and translation to OBS. They make very different trade-offs. Here is the honest breakdown — including the things Caption.Ninja does not mention upfront.
No credit card. 6-hour free trial. Works on any browser.
?server=google&key=YOUR_KEY&lang=ja-JP| Feature | StreamTranslate | Caption.Ninja |
|---|---|---|
| Cost (casual streamer) | $9.99 one-time / $14.99 mo | Free |
| Speech recognition | Deepgram Nova-3 (server-side, reliable) | Chrome/Edge Web Speech API (deprecating, broken in Chrome) |
| Browsers that work | Chrome, Safari, Firefox, Edge — any | Microsoft Edge only (Chrome broken, Safari/Firefox unsupported) |
| Languages out of the box | 30+ languages included | 17 European (free) — others need your own Google API key |
| Asian/MENA languages | Included, no setup | Requires Google Cloud account + API key + billing management |
| Setup complexity | One URL paste into OBS | Manual URL parameters, API key config, optional JSON credentials |
| Privacy | Audio goes to Deepgram server | Audio stays local (Bergamot ML model) |
| Open source | No | Yes (GitHub) |
| Self-hostable | No | Yes |
| Dual-language display | Yes (Pro+) | No |
| Speaker diarization | Coming soon | Single mic only |
| Real-time word-by-word | Yes | Sentence-by-sentence |
| API billing risk | None — fixed subscription | You manage Google Cloud spend limits yourself |
| Email/chat support | Yes (paid plans) | GitHub issues only |
Cost. Free is hard to beat. For a casual streamer who only needs European languages, is comfortable with technical setup, and uses Edge — Caption.Ninja is cheaper than us by definition.
Privacy. Mozilla Bergamot runs entirely on your machine. No audio leaves your computer. For privacy-conscious streamers, journalists, or EU-regulated content, this is a real advantage we cannot match.
Open source. The code is on GitHub. You can fork it, self-host it, audit it. We are proprietary closed source.
Flexibility. Caption.Ninja supports OpenAI-compatible endpoints including local Ollama, Anthropic Claude, and custom HTML/CSS overlay styling. For developers who want full control, that depth is real.
It works in Chrome. Caption.Ninja does not right now — Google is killing the Web Speech API it depends on. We use Deepgram server-side. Not affected by any browser change, ever. Full technical breakdown here.
Zero API key management. No Google Cloud account. No billing dashboard to watch. No URL parameters to construct. No risk of a surprise $300 charge because you forgot to set a spending cap. Paste one URL, done.
Every browser. Caption.Ninja requires Edge. We work in Chrome, Safari, Firefox, and Edge — whatever you have open.
Asian and MENA languages. Japanese, Korean, Mandarin, Hindi, Arabic, Thai, Vietnamese — all included. No extra setup. Caption.Ninja's free tier cannot do any of these.
Dual-language display. Show the original spoken text and its translation simultaneously, live on stream. Caption.Ninja only shows one language at a time.
Multi-speaker support coming soon. StreamTranslate is building dual-mic support to label multiple speakers separately. Caption.Ninja is limited to a single microphone input.
Use Caption.Ninja if: you stream in European languages only, you are comfortable with Edge browser and API key configuration, privacy is more important than reliability, and you want open source or self-hosted.
Use StreamTranslate if: Caption.Ninja is broken for you, you stream in Asian or MENA languages, your viewers use Safari or Firefox, you want setup to take 60 seconds instead of an afternoon, or you do not want to manage Google Cloud billing.
No credit card. One URL pasted into OBS. Live in 60 seconds. Works in every browser.
Launch StreamTranslate →