Subtitle tools that just work — and never upload your files
Convert, re-time, repair and clean SRT, WebVTT, ASS and other subtitle files. Everything runs on your device, so even private videos stay private.
- Free, no signup
- Files never leave your browser
- SRT · VTT · ASS · SBV · SUB · LRC
- Works on desktop and mobile
Timing & Sync
Shift, stretch and re-time subtitles so they match the video.
Convert Formats
Switch between SRT, WebVTT, ASS, SBV, SUB, LRC, CSV and plain text.
- SRT to VTT ConverterTurn SubRip .srt files into WebVTT for HTML5 video.
- VTT to SRT ConverterConvert WebVTT files to widely supported SubRip.
- ASS to SRT ConverterStrip ASS/SSA styling and get clean, compatible SRT.
- SRT to ASS ConverterCreate styled ASS subtitles with your own font, size and colours.
- SRT to TXT ConverterExtract the plain text from a subtitle file.
- SRT to CSV ConverterExport subtitles to a spreadsheet-friendly CSV file.
- CSV to SRT ConverterBuild an SRT file from a spreadsheet of start, end and text.
- SBV to SRT ConverterConvert YouTube .sbv captions to SRT and tidy auto-captions.
- SUB to SRT ConverterConvert text-based MicroDVD .sub files to SRT.
- LRC to SRT ConverterTurn synced song lyrics (.lrc) into SRT subtitles.
- SRT to LRC ConverterCreate synced lyrics (.lrc) from subtitle files.
- TXT to SRT ConverterTurn a script or transcript into timed subtitles automatically.
Fix & Clean
Repair encodings, clean up text, merge, split and check subtitle files.
- Subtitle Encoding FixerRepair garbled characters and convert any subtitle file to UTF-8.
- Bilingual Subtitle MergerCombine two languages into one dual-language subtitle file.
- SRT CleanerRemove tags, sound descriptions, ads and duplicate lines.
- Remove SDH from SRTDelete sound descriptions and speaker labels for hearing-impaired subs.
- SRT SplitterCut a subtitle file at a time or into equal parts.
- SRT JoinerCombine several subtitle files (CD1 + CD2) into one timeline.
- SRT Checker & FixerFind timing, overlap and format errors in a subtitle file.
- Subtitle Reading Speed CheckerMeasure characters per second, line length and duration for every cue.
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Why use SubtitleLab?
- Private by designSubtitle files are read and written by JavaScript in your own browser tab. There is no upload, no account and nothing to install.
- Made for real problemsOut-of-sync lines, drifting timing, ??? instead of accents, YouTube duplicates, hearing-impaired text — each has a tool with sensible defaults.
- Keeps your formattingOnly what you ask to change is changed. Styles, positions, italics and original line breaks are preserved where the format allows it.
- Batch readyDrop several files at once, convert them all, and download them together as a ZIP.
Guides
- SRT vs VTT vs ASS: Which Subtitle Format Should You Use?A plain-English comparison of SRT, WebVTT and ASS subtitle formats: features, compatibility, styling and when to choose each one — with conversion links.
- How to Fix Out-of-Sync Subtitles: Delay, Drift and FPSSubtitles too early, too late or slowly drifting? Learn how to diagnose the problem and fix it with a shift, a two-point sync or a frame-rate conversion.
- Why Subtitles Show Strange Characters (and the Fix)Question marks, “é” or boxes instead of letters? Learn how text encodings work, how to recognise the cause of garbled subtitles and repair the file.
- Subtitle Timing and Reading Speed GuidelinesHow long should a subtitle stay on screen? Learn the standard limits for characters per second, line length, lines per cue, minimum and maximum duration.
- How to Add Subtitles to an HTML5 Video With WebVTTAdd captions and subtitles to the HTML5 video element with a track tag and a WebVTT file. Covers languages, default track, styling, CORS and common problems.
- How to Extract Subtitles From an MKV or MP4 Video FilePull embedded subtitle tracks out of an MKV or MP4 video with MKVToolNix or FFmpeg, and learn what to do with image-based PGS and VobSub subtitles.
Frequently asked questions
Are my subtitle files uploaded to a server?
No. All tools run locally in your browser using JavaScript. Files are never sent to us, and they disappear when you close or reload the page.
Which subtitle formats are supported?
SRT, WebVTT (VTT), ASS/SSA, SBV (YouTube), MicroDVD SUB, LRC lyrics, CSV and plain text. Image-based subtitles (VobSub, PGS) need OCR software and cannot be handled in the browser.
Why are my subtitles out of sync?
Usually a constant offset, a frame-rate difference (for example 23.976 vs 25 fps) or a different cut of the video. Our sync guide explains how to tell them apart and which tool to use.
Why do my subtitles show strange characters?
The file is saved in a different text encoding from the one your player expects. The encoding fixer detects and repairs it.
Is SubtitleLab free?
Yes. The site is supported by advertising, which keeps the tools free without registration.
Can I use it on my phone?
Yes, the tools work in modern mobile browsers. Large files are processed faster on a computer.