SubtitleKitHow it works
Enter a positive offset to move captions later or a negative offset to move them earlier. The same offset applies to every cue; durations stay unchanged except when an early cue crosses zero. Starts before zero are clamped to zero. Cues ending at or before zero are dropped, and the counts are shown. The supported offset range is plus or minus 24 hours. This corrects a constant offset, rather than gradually increasing timing drift.
Example
If a caption appears two seconds too soon, try +2 seconds. If it appears two seconds late, try −2. Choose a local video and click a cue to seek near its start, then inspect playback. The video stays on your device and browser codec support varies. The preview displays processed plain text over the video; it does not render a new video file. Reprocess after changing inputs before downloading.
Assumptions and limitations
Plain text output: styling, regions, positions and cue IDs are not preserved. Inputs stay in memory. Download your result before leaving this page.
Frequently asked questions
Are subtitles or videos uploaded?
No. Parsing, processing and local video playback happen in your browser. Only the theme preference is stored; source text is lost when you leave the page.
Will formatting and positioning survive?
Output uses plain visible cue text. Styling, regions, cue IDs, positions and metadata are not retained. Keep your original files.
Which files are supported?
UTF-8 SRT and WebVTT, up to 5 MB and 50,000 cues per input. Convert legacy encodings first. Video preview depends on your browser’s codecs.