Free subtitle generator with no watermark
OpenSubs (opensubs.app) writes subtitles from a video's speech in your browser and burns them into an MP4 with no watermark. No account, no upload, no file-size limit, and no paid plan that removes a logo, because there is no logo.
Free and open source (AGPL-3.0-or-later).
Four things you can check
Every free subtitle generator says something like this. Here is what each claim means on OpenSubs, and how to check it yourself.
No watermark
The burned MP4 contains your video and your subtitles, nothing else: no logo, no end card, no “made with” line. Signed in or not, the export is the same.
No account
Transcribing, editing, the 12 styles, word-by-word highlighting, trimming, burning and every export work signed out. An account is only for the optional paid cloud translation.
No upload
Whisper runs in the tab and the video is read from your disk; the product has no upload endpoint. Open the Network tab while you work: on the default route, the audio and video are never in a request.
Free
All of the above costs nothing. The one paid option is translation on our backend, at $5 for 1,000 credits, priced before it runs. Free translation runs on your device in desktop Chrome 138 or later.
Why there is no watermark or size limit
Hosted editors watermark the free tier and cap the file size because your file has to reach their server, and the server pays for the encode. Here the encode runs on your own machine, with WebCodecs, so neither cost exists. The trade-off is speed: a long video on a laptop takes a while, and the desktop app (macOS, Windows, Linux) is the better choice for very long files.
Subtitles in four steps
- Open opensubs.app and choose a video (MP4, MOV, WebM or MKV).
- Press Generate from the audio. The speech model downloads once, from 40 MB to 250 MB depending on the size you pick.
- Fix any line in the Subtitles tab and pick a style.
- In Export, burn them into an MP4, or save .srt, .vtt, .ass or .txt.
Already have an .srt? See burn subtitles into video. Comparing hosted editors? See the VEED and Kapwing comparison.
What it will not do
- Change timings. You can rewrite a line, not move it, and lines cannot be added or deleted.
- Add a soft subtitle track inside the MP4. It burns them in, or gives you the file.
- Run the recogniser in Safari on iOS 17. iOS 26 works.
The source is public on GitHub. Questions, or a problem to report: hello@opensubs.app.
Questions
Does OpenSubs add a watermark?
No. The burned MP4 has your video and your subtitles and nothing else, on the free route, signed in or not.
Do I need an account?
No. Everything that runs in your browser works signed out. An account is needed only for optional paid cloud translation.
Is my video uploaded?
No. Whisper runs in your browser and the video is read from your disk. Only the speech model is downloaded, once.
Is there a file-size limit?
We set none, because nothing is uploaded. A long video is a long encode on your machine; for very long files the desktop app is the better choice.
What costs money?
Only translation on the OpenSubs backend, at $5 for 1,000 credits, with the price shown first. Transcribing, styling, burning, exports and on-device translation are free.