Review cue duration, gaps, overlaps, line length and Unicode reading speed using thresholds you choose.
Your input
Outputs are cleared when the input changes.
Result
Enter your data or use the example, then run the tool.
Worked example
Ten non-whitespace characters in two seconds give 5 CPS. The next cue beginning at 2.5 seconds overlaps the first cue ending at 3 seconds by 500 ms.
Method
Strip basic i/b/u tags, decode basic HTML/numeric entities and count Unicode code points excluding whitespace; punctuation counts and emoji sequences may count as multiple points. Report duration, CPS, long lines, ordering, overlaps and gaps without changing the input.
Limits
Each input: at most 2 MiB UTF-8 and 10000 cues, output 4 MiB, timeline seven days. Plain cues only: WebVTT settings/NOTE/STYLE/REGION/timestamp maps and advanced markup are rejected. Unicode and basic i/b/u are preserved; no speech recognition. Large bounded operations may briefly occupy the main thread. Not platform certification, proofreading or automatic repair; reading-speed needs vary by language and audience.
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When switching languages, text, settings and selected files are temporarily kept on this device. Transfers are removed after restoring; interrupted transfers are cleaned up on a later visit. Inputs and files are never uploaded.