How to use it
Choose the file
SRT and WebVTT files work. The page reads the file in your browser and shows how many subtitle lines it found.
Pick the languages
Choose the language the subtitles are in and the language you want. The first time you use a pair, your browser downloads its translation model, a few tens of megabytes, and keeps it for next time.
Translate and save
A film's worth of subtitles takes about a minute on a recent laptop. Save the result as a new file next to the original. Tick the box to keep the original line above each translated one. The file has to be saved as UTF-8, which most subtitle files are.
What happens to your file
It stays on your computer. The file is read by your browser and translated by a model running in this tab. There is no upload, no account and no limit on how many files you translate.
Apart from the page itself, the only downloads are the list of languages, the translation engine and the model for the language pair you choose. The models are the open ones Mozilla builds for Firefox's offline page translation, the same family our desktop app uses. The engine is served by this site. The models are passed to you from Mozilla's public storage through this site, without your cookies, so our server sees which language pair you asked for, and Mozilla's storage sees our server, not you. Like the rest of this site, the page counts visits and finished translations without cookies, and those counts never include the file, its name or the languages.
What to expect from the translation
- About 50 languages to or from English. Any other pair goes through English, in two steps, which costs some accuracy.
- It translates one subtitle at a time. Sentences split across two subtitles can come out less natural than a whole sentence would.
- Names, slang, jokes and song lyrics are where machine translation goes wrong. Skim the result before you publish it.
- Timings, order and line numbers are kept exactly. Italic and other tags are removed, and a subtitle that ran over two lines comes back as one.
When there is no subtitle file at all
This page needs subtitles that already exist. For a video, stream or call that has none, the text has to come from the audio. Fraze is our desktop app for that: it listens to whatever your computer plays, writes captions as people talk and shows a translation under each line, with the work done on your computer.
It is a paid app after a free first 30 minutes: $29.99 once or $2.99 a month. It works live only, so it does not produce a subtitle file for a video you have not played.
Questions
Is my subtitle file uploaded?
No. The file is opened and translated inside your browser. After the translation model has downloaded you can switch your connection off, keep the page open, and keep translating with the same two languages.
How do I translate an SRT file?
Choose the SRT file, pick the language it is in and the language you want, and press Translate. When it finishes, save the new SRT file. The timings are identical, so it lines up with the same video.
Can it make dual subtitles?
Yes. Tick Keep the original line and each subtitle in the new file shows the original text with the translation under it, which is what language learners usually want.
Which languages does it support?
About 50 languages to or from English, including Spanish, French, German, Italian, Portuguese, Dutch, Polish, Ukrainian, Russian, Turkish, Arabic, Hindi, Chinese, Japanese and Korean. The list in the tool is the current one, because it follows the models Mozilla has released. Pairs without English in them are translated in two steps through English.
Is it really free? What is the catch?
It is free with no limit and no account. It costs us almost nothing to run, because your computer does the work. We make Fraze, a paid desktop app for live captions and translation, and this page is one way people find it.
Which translation engine does it use?
Bergamot, the open source engine behind Firefox's offline translation, compiled to WebAssembly, with Mozilla's Firefox Translations models. Engine and models are published under the Mozilla Public License 2.0.