SubtitleRocketWhat does the subtitle checker flag?
It reports parse problems, end times before start times, overlapping cues, very short or long cue durations, more than two lines, long lines, and reading speed above the displayed CPS threshold.
Free subtitle tool · runs in your browser
Check subtitle timing and readability before export
A subtitle file can parse correctly and still be difficult to watch. This checker reviews practical delivery problems—overlapping cues, invalid timing, very short or long displays, more than two lines, lines over 42 characters, and reading speed above 20 characters per second.
Subtitle file
Nothing checked yet
Paste subtitles or open a file. The report appears here without uploading anything.
Checks use 20 characters/second, 42 characters/line, two lines/cue, 0.7-second minimum, and 10-second maximum.
FAQ
Does a clean report prove the words match the audio?
No. File checks can verify structure, timing relationships, and readability, but only a review against the final video can confirm transcription accuracy and sync.
Can I check both SRT and VTT?
Yes. Paste either format or open an .srt, .vtt, or .webvtt file. WebVTT is detected from its header or filename.
Is the subtitle text sent anywhere?
No. Parsing and analysis run locally in your browser.
Need the captions on the video itself?
These utilities handle subtitle files. To generate captions from speech, style them, and burn them into an MP4, open the full editor; free 720p export, no signup to start.