Quality checks

Detect structural subtitle defects: overlaps, gaps, empty cues, non-monotonic timing and unusual cue durations — one page per problem or all at once.

9 tools

Find Empty Subtitles

List every cue that holds no text at all — a subtitle occupying the timeline while showing nothing, which no reading of a file makes correct.

Find Gaps Between Subtitles

List every stretch of blank screen wider than the limit you set, measured from the last cue that was still on screen rather than from the cue before it.

Find Out-of-Order Subtitles

Report files whose cues were not in time order, using the reorder the reader had to perform — so the answer does not depend on which subtitle format you happen to hold.

Find Overlapping Subtitles

List every cue that starts before the previous one has finished — a report you can download, with the cue numbers, the times and the overlap measured in milliseconds.

Find Subtitles That End Before They Start

Report cues whose recorded end time was not later than their start time — zero-length and back-to-front timecodes alike, counted while the file was being read.

Find Subtitles With No Dialogue

List every cue with no letters in it: music notes, bare numbers, dashes. Captions use these on purpose, so the report flags them for a look rather than as faults.

Find Too-Long Subtitles

List every cue still on screen after the maximum you set — subtitles that outstay their line, with the measured duration and your limit printed next to each one.

Find Too-Short Subtitles

List every cue on screen for less time than the minimum you set, with the measured duration and your limit side by side. Nothing in the file is changed.

Scan Subtitles for Structural Problems

Run every structural check at once — overlaps, gaps, empty cues, out-of-order cues, impossible durations and odd ones — and report the count for each in one pass.

Other categories

Format conversion

Move subtitles between SRT, WebVTT, ASS, SSA, SBV, SMI, LRC, MicroDVD, TTML, JSON, plain text and CSV — and see what each conversion drops before it runs.

Shift, scale, re-frame and re-align subtitle timing: frame-rate conversion, overlap and gap repair, trimming to a range and splitting a file into parts.

Text and styling

Change case, strip tags and SDH descriptions, recolour or reposition lines, merge or split bilingual tracks, find and replace, rewrap lines, fix encoding.

Accessibility compliance

Check subtitles against reading speed, line length and display-duration thresholds from EN 301 549, WCAG 1.2.2, FCC, Ofcom, Netflix and BBC rules.

Re-label subtitle timecodes between 30 fps non-drop and 29.97 drop-frame, two conventions that drift 3.6 seconds apart every hour, in both directions.

Export and integration

Turn subtitles into an HTML track element, a YouTube chapter list, a plain text transcript or a printable PDF — outputs no subtitle format can carry.

Extract subtitle tracks from video, transcribe speech with Whisper, OCR PGS and VobSub bitmaps, voice subtitles and resync audio — all inside your browser.