Subtitle Edit · online · free · private
Subtitle Edit Online: edit subtitles in your browser
Open an SRT, VTT or ASS file, fix text and timing right on the video, find errors automatically and export again – like the desktop app Subtitle Edit, without installing anything. Everything runs in your browser; your video and subtitles are never uploaded.
| # | Start | End | Duration | CPS | Text |
|---|
Runs entirely in your browser. Changes are saved locally so nothing gets lost. Space plays, S and E set start and end.
- No upload
- SRT · VTT · ASS · SBV · SUB
- Waveform & video
- Sync tools
- Error check
- Auto subtitles (Whisper)
What is Subtitle Edit?
Subtitle Edit is a free, open-source subtitle editor by Danish developer Nikolaj Lynge Olsson (Nikse). It is one of the best-known subtitle tools: edit lines and timings, sync against video and waveform, convert between more than 300 formats, turn image-based subtitles into text with OCR, spell-check, and create subtitles with speech recognition. The source code is on GitHub under the GPL; the official site is nikse.dk.
Subtitle Edit Online is not an official version. It is an independent browser editor for the most common jobs: quickly fix an SRT, sync subtitles to a video, find errors and export to another format. For OCR, exotic formats or heavy batch work, the desktop app is the better choice.
Supported formats
| Format | Extension | Typical use |
|---|---|---|
| SubRip | .srt | The standard for video players, YouTube and video editors |
| WebVTT | .vtt | HTML5 video, streaming, Vimeo, e-learning |
| Advanced SubStation Alpha | .ass / .ssa | Anime, fansubs, styled subtitles (styles are kept on export) |
| YouTube SubViewer | .sbv | Downloads from YouTube Studio |
| MicroDVD | .sub | Older players, frame-based timing (frame rate selectable) |
| Text / JSON | .txt / .json | Plain text without times, or timings for your own scripts |
Character encoding is detected automatically (UTF-8, UTF-16, legacy Windows encoding). Exports are always UTF-8.
Features at a glance
Every line with start, end, duration and reading speed. Click a line to jump to it in the video.
Open a local video and see the subtitles on top. Drag start and end directly in the timeline.
Shift all times, stretch them between two points, or convert 23.976 to 25 frames per second.
Overlaps, too short or too long on screen, reading speed too fast, lines over 42 characters.
Trim overlaps, extend short lines, rewrap long lines, delete empty lines.
Speech recognition with Whisper in your browser turns video or audio into ready subtitle lines.
Subtitle Edit Online or the desktop app?
| Subtitle Edit Online | Subtitle Edit (desktop) | |
|---|---|---|
| Installation | none, runs in the browser | download for Windows, macOS, Linux |
| Formats | SRT, VTT, ASS/SSA, SBV, SUB, TXT, JSON | more than 300 |
| Video, waveform, sync | yes | yes, plus spectrogram |
| Speech recognition | Whisper in the browser | Whisper and other engines |
| OCR (Blu-ray SUP, DVD VobSub) | no | yes |
| Privacy | files stay in the browser | files stay on your PC |
How to edit subtitles online
- Open your subtitles. Choose a file with “Open subtitles” or just drag it into the editor. No file yet? Start with “New” or load the example.
- Add the video. Use “Open video/audio” to load the matching video. The subtitles appear on the picture and the waveform below.
- Fix text and timing. Click a line and edit the text in the box below. Set start and end by typing, with the buttons at the playback position (keys S and E), or by dragging in the timeline.
- Synchronize. If everything is early or late by the same amount, use “Shift”. If the offset grows over time, use “Two-point sync” or “Change frame rate”.
- Check for errors. The red counter shows problems. Click it to jump to the next one; “Fix errors” repairs overlaps, duration and line length automatically.
- Export. Pick a format (SRT, VTT, ASS …) and click “Export”. The file is saved straight away.
Good subtitles: the key rules
- Two lines at most, around 42 characters each.
- Reading speed (CPS = characters per second) around 15–20, lower for children’s content. The editor flags lines above your limit.
- Duration at least about 0.7 seconds, at most 7 seconds.
- A small gap between subtitles (one or two frames, roughly 40–80 ms) so the eye notices the change.
- Break lines sensibly: don’t split an article from its noun; keep the top line shorter.
Keyboard shortcuts
Space play/pause · ↑/↓ previous/next line · S start at playback position · E end at playback position · Ctrl+Z/Ctrl+Y undo/redo · Ctrl+wheel zoom the timeline.
Do more with Webtools Pro
The editor is free. Webtools Pro from Answer the Web adds larger Whisper models, long videos and batch conversion – plus every other Answer the Web tool.
- Whisper small and large-v3-turbo for more accurate auto subtitles
- Videos and audio longer than 5 minutes
- Convert many subtitle files at once
- Also works on MarkItDown, WhisperX Online and all ATW webtools