Caption & Subtitle QC Validator
Load an SRT or WebVTT file and check every cue against a real delivery profile. The validator reports reading speed, characters per line, line count, overlapping cues, tight gaps, cue duration and the text problems that break some players.
Open an SRT or WebVTT file, or paste the subtitle text to start.
Questions about caption & subtitle qc validator
Which formats are supported?
SubRip (.srt) and WebVTT (.vtt). Both are read with the usual rules: a timing line with an arrow between two timestamps, optional cue numbers or identifiers, and the text underneath.
Where do the limits come from?
The built-in profiles follow published delivery practice. The Netflix English timed text style guide asks for no more than 42 characters per line, no more than two lines, and a reading speed of up to 20 characters per second for adult programmes and 17 for children's. Other languages are held to 17 and 13. You can also set your own limits.
How is reading speed measured?
Every visible character in the cue, spaces included, divided by the length of the cue in seconds. Markup tags are removed first, so a line of styling does not count towards the speed.
Does it check the subtitles against the video?
No. Without the video it cannot see whether a cue is timed to the dialogue or to a shot change, so it checks the file on its own terms: the timings, the text and the profile limits.
What does the clean-up button change?
Only whitespace. It strips trailing spaces, collapses double spaces, removes zero-width characters, turns non-breaking spaces into ordinary ones and tidies blank lines. It never rewrites a word or moves a timestamp.
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