Private subtitle toolkit

Free online subtitle tools to sync and fix any file.

A free subtitle toolkit that runs online in your browser. Add subtitles to a video and fix the sync while you watch, convert between every common format, generate SRT from plain text, and repair, edit or clean up any subtitle file in seconds — no upload, no sign-up.

Sync subtitles See all tools

100% private
No sign-up
Free forever
SRT · VTT · ASS · SBV · SUB · SMI · LRC · TTML

Every free subtitle tool, in one place

Pick a task. Each online tool does one thing well, and runs entirely in your browser.

Sync Subtitles Shift every cue by an exact offset so captions line up perfectly. Auto-Sync to Reference Automatically retime a subtitle to match a correctly-synced one. Subtitle Editor Edit subtitle text and timings cue by cue, then export any format. Add Subtitles to Video Play your video with any subtitle file and fix the sync live. Subtitle Converter Convert between SRT, VTT, ASS/SSA, SBV, SUB, SMI, LRC and TTML. Text to SRT Generator Turn a plain-text transcript or script into a timed SRT file. Frame Rate Converter Rescale timings between frame rates to fix subtitles that drift. Encoding Repair Fix garbled subtitle characters by re-decoding them to UTF-8. Merge & Split Combine two SRT files into one, or split one file in two. Cleanup Tools Remove SDH/hearing-impaired tags, strip formatting, check CPS. Subtitle to Text Strip timecodes to get a clean transcript from any subtitle file.

Popular subtitle conversions

Jump straight to the conversion you need — each one is instant and runs in your browser.

SRT → VTT VTT → SRT ASS → SRT SRT → ASS SUB → SRT SRT → SUB SBV → SRT SRT → SBV SMI → SRT TTML → SRT LRC → SRT SRT → LRC All formats →

How it works

Drop your file

Drag in an SRT, VTT or ASS/SSA file, or click to browse. It loads instantly.

Make the fix

Convert, re-time, rescale, repair encoding or clean up. The result previews as you go.

Download

Save the finished subtitles in the format you need. Nothing is ever uploaded.

How to sync subtitles in any player

Step-by-step instructions for fixing out-of-sync subtitles in the apps people use most.

Learn how subtitles work

In-depth, plain-English guides to subtitle formats, sync problems, encoding and more.

All guides

7 min read SRT, VTT and ASS subtitle formats explained What SRT, WebVTT and ASS/SSA actually store, how they differ, and which one to reach for in each situation. 6 min read Why subtitles go out of sync, and how to fix them Diagnose the two kinds of sync problem, a constant offset versus gradual drift, and learn the right fix for each. 6 min read Garbled subtitle characters, explained and fixed What causes mojibake, why it is an encoding mismatch rather than corruption, and how to recover the original text. 6 min read Subtitle frame rates and the 23.976 vs 25 fps problem Why a frame-rate mismatch makes subtitles drift, where 23.976 and 25 fps come from, and how rescaling fixes it.

Questions, answered

Are SubAlign’s subtitle tools free?

Yes. Every tool is completely free with no sign-up and no usage limits. The tools are free to run because the processing happens on your own device rather than on a server.

Do my subtitle files get uploaded anywhere?

No. All processing happens locally in your browser. Your files never leave your device, which is also why the tools are free to run.

Which subtitle formats does SubAlign support?

SubAlign reads and writes SubRip (.srt), WebVTT (.vtt), Advanced SubStation (.ass/.ssa), YouTube SBV (.sbv), MicroDVD (.sub), SAMI (.smi), LRC lyrics (.lrc) and TTML/DFXP (.ttml) — and can generate a timed SRT from plain text.

Do I need to install anything?

No. SubAlign runs in any modern web browser on desktop, tablet or mobile. There is nothing to download or install.