Add subtitles to a video online

Watch any video with any subtitle file — without installing anything

You have a video file and a subtitle file, and you just want to watch them together, or check that they match before a flight, a class or a screening. This page turns your browser into that player. Pick the video, drop in the subtitles — SRT, VTT, ASS, and the rest — and playback starts with the subtitles rendered on top. Whatever format you drop in is converted to WebVTT behind the scenes, because that is the one format browsers render natively.

Everything happens on your machine. The video is played straight from your disk via your browser's own decoder, the subtitle is parsed in JavaScript on the page, and neither file is uploaded anywhere — which also means there is no length limit, no queue and no watermark.

Fix the sync while you watch

This is the part a normal player makes tedious. If the subtitles trail the dialogue, tap −0.1s or −0.5s until they land on the beat — the change applies instantly, while the video keeps playing. When it feels right, hit Download synced subtitles and you get your subtitle file with that correction baked in, ready for any player. It is the same fix the sync tool applies by the numbers, but here you do it by eye and ear.

One caveat: a constant offset fixes subtitles that are uniformly early or late. If they start in sync and drift further out as the video plays, the subtitle was made for a different frame rate — run it through the frame-rate converter instead.

Soft subtitles vs. burned-in subtitles

What this page gives you is soft subtitles: a separate text track shown over the video, the same way VLC or a TV shows an .srt next to a movie file. That is what you want in almost every case — it is instant, lossless and the text stays editable. The alternative, burning the text into the picture itself, requires re-encoding the entire video and only makes sense when the destination cannot show a text track at all (an old device, or a social platform that ignores caption files). For that, and for keeping subtitles permanently with the file, see the guide on how to add subtitles to any video.

My video won't play here — why?

The page uses your browser's built-in video decoder, so it plays what your browser plays: MP4 (H.264/H.265), WebM and most MOV files work everywhere. MKV and AVI containers usually don't — that is a browser limitation, not a file problem. Two easy outs: open the same subtitle file in VLC alongside the video, or if you only need to check and fix the subtitle timing, do it with the sync tool using a timestamp you read from the audio. Chrome tends to have the broadest codec support if another browser refuses a file.