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Subtitle utility

Fix Out-of-Sync Subtitles

Fix out-of-sync subtitles online for free. Shift SRT, VTT, or ASS captions earlier or later in milliseconds locally with no upload.

Free No signup Browser-local

Subtitle input

No signup. No server upload. Browser-only processing.

Drop a subtitle file here or choose one manually

Supports SRT, VTT, and ASS where relevant to the tool.

Selected file: sample.srt

Use positive numbers to delay captions and negative numbers to move them earlier.

Synced subtitle output

Runs locally in your browser

Selected file: sample.srt

Workflow notes

How to use this Fix sync tool

Use this when every subtitle cue is consistently ahead of audio or behind speech by the same amount. Enter a millisecond offset, shift the whole SRT, VTT, or ASS file earlier or later, and export a synced copy locally with no upload. If only one section is out of sync, use the partial shifter instead.

  1. Add a supported subtitle file. Upload or paste a supported subtitle file (.srt, .vtt, .ass, .ssa, .txt), or load the sample input to see the expected structure.
  2. Run the Fix sync tool. Use the browser-based converter or repair action to process the subtitle file locally on your device.
  3. Review and download the output. Check the first few cues, the middle of the file, and the final cue before copying or downloading the result.

Input and output checklist

  • Use a complete subtitle file with valid cue timing when possible.
  • Keep a copy of the original file before replacing it in your workflow.
  • Review the first few cues, the middle of the file, and the final cue after export.
  • Test the downloaded output in the destination player, editor, or upload form.

Common mistakes to avoid

  • Using a whole-file sync fix when only one scene is wrong.
  • Not checking the beginning and end of the output file.
  • Replacing the original file before confirming the timing in the target player.

All processing runs in your browser, so the subtitle or video file does not need to be uploaded to a server. That is useful for client review files, unreleased videos, internal training material, and other caption workflows where the text should stay on your device.

When to use this tool

Use this free sync fixer when every subtitle cue is ahead of audio or behind speech by the same offset and you need a local whole-file timing correction.

  • Move out-of-sync subtitles earlier or later in milliseconds.
  • Fix captions that are consistently ahead of audio or behind speech.
  • Repair captions after a video export changed timing.
  • Fix a constant timing offset across the whole file.
  • Create a synced SRT, VTT, or ASS copy for review or upload.

FAQ

Can I fix out-of-sync subtitles online for free? +

Yes. You can shift SRT, VTT, and ASS subtitle timing for free in your browser without signup or upload.

Can this fix subtitles that drift over time? +

This tool fixes a constant whole-file offset. If subtitles drift more over time, compare the first and last cues and use a drift retiming workflow instead.

Should I move subtitles earlier or later? +

Use a negative millisecond value when subtitles appear too late and need to move earlier. Use a positive value when subtitles appear too early and need to be delayed.

Should I use this for one out-of-sync scene? +

Use this tool only when the whole file has the same offset. If one scene or middle section is wrong after an edit, use the partial subtitle shifter so the rest stays in sync.

Are my subtitle files uploaded to a server? +

No. Sync fixes run locally in your browser, so your subtitle file stays on your device.