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Check SRT or WebVTT Subtitle Timecode Errors

Check subtitle timecodes, cue order, and start/end times before import.

Check subtitles

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How to use it

Paste SRT or WebVTT subtitle text and check basic timing issues while counting recognized cues. It flags an end time that is not later than its start, overlaps with the previous cue, and a missing WEBVTT header when VTT is selected.

  1. Choose Auto, SRT or WebVTT and paste the subtitle text.
  2. In Auto, text beginning with WEBVTT is treated as VTT; everything else is treated as SRT.
  3. Review the cue count and reported timing issues, then correct the source subtitle.
Timing
start must be earlier than end
Overlap
warns when the next start is before the previous end
WebVTT
checks for leading WEBVTT
Scope
basic timing check, not a complete subtitle-spec validator

A cue beginning at 00:00:03,500 overlaps one that ends at 00:00:04,000

If the previous cue is 00:00:01,000 --> 00:00:04,000 and the next starts at 00:00:03,500, the checker reports an overlap.

It does not fully validate SRT sequence numbering, every WebVTT grammar rule or markup inside cue text. Treat a clean result as “no basic timing issue found,” not as certification that every platform will accept the file.

Auto mainly distinguishes VTT by its header

When the trimmed text begins with WEBVTT it is treated as WebVTT; otherwise Auto falls back to SRT. Explicitly select VTT when diagnosing a damaged header.

Reversed or zero-length timing is flagged

A cue whose end is equal to or earlier than its start is reported so you can find basic timestamp mistakes quickly.

Overlap is compared with the previous cue

Overlaps can be intentional in some subtitle styles, so the warning is something to review rather than an unconditional production failure.

No recognized timecodes produces a clear warning

This helps distinguish an empty/wrong paste from a subtitle with only a few local timing issues.

The destination platform remains the final authority

YouTube, editing software and streaming systems can impose additional syntax or duration rules. Test the corrected file in the actual destination workflow.

Related references: DPI, PPI & px · Paper sizes · Aspect ratios