FREE TOOL · SUBTITLES

Subtitle sync fixer for SRT and VTT files

This free subtitle sync fixer shifts every cue of an SRT or VTT file earlier or later, fixes drift that grows over the video by stretching between two points you choose, and converts SRT to VTT and back. The file never leaves your browser.

  1. 1

    Open your subtitle file

    Drop an .srt or .vtt file, or paste its text. Cues that cannot be read are listed by number and line, and the rest are kept.

  2. 2

    Shift or stretch

    If every line is late by the same amount, shift all cues by a number of milliseconds. If the delay grows over the video, give two cues their correct times and the timing between them is stretched to match.

  3. 3

    Download in the format you need

    Save as SRT or WebVTT. Text, line breaks and VTT cue settings are kept as they were.

Constant offset or progressive drift: which fix to use

When the first line is half a second late and the last line is also half a second late, the subtitles have a constant offset: one shift fixes the whole file. When the first line is on time but the last line is several seconds late, the subtitles drift, usually because they were timed against a version of the video with a different frame rate or an extra intro. A shift cannot fix drift; a stretch between two anchor cues can.

Pick an early cue and a late cue, type the time each one should start at, and every cue in between is moved in proportion. Check a line in the middle afterwards: if it is still off, the edit is not linear (a cut was removed in one place) and the file needs to be fixed in two parts.

Subtitle sync questions

Is my subtitle file uploaded anywhere?+

No. The file is read and rewritten by your browser; nothing is sent to ClipFlap or anyone else, which is why the tool also works on unpublished projects.

What is the difference between SRT and VTT?+

Both list cues with a start time, an end time and text. SRT numbers each cue and uses a comma before milliseconds; WebVTT starts with a WEBVTT header, uses a dot and can carry cue settings such as position. Most players and platforms accept both.

Why are my subtitles late at the end but fine at the start?+

That is drift, not an offset. It usually comes from a frame-rate difference (25 versus 23.976 fps) or a timing made on another cut of the video. Use the stretch with an early and a late anchor cue.

Can I shift subtitles to start earlier than zero?+

Cues are never placed before zero. A cue that would end before the video starts is removed and the remaining cues are renumbered, so the file stays valid.

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Captions that are timed from the start

ClipFlap times every caption word by word from the audio, so clips never need a sync pass.