VIDEO & PUBLISHING
Subtitle Workbench
Get the words and timing right.
Edit captions, check against video, and review what your export keeps.
Start with your subtitles
Choose a file, paste its text, or try the sample. Your existing document stays until a new import succeeds.
Subtitle source
Edit the complete source, then use Import full source to update the cues. Unedited source is kept exactly; editing normalizes line endings to LF. Tab leaves the editor. Use Find or replace to reach text anywhere in a large file.
UTF-8 is required for WebVTT. Invalid bytes stop import. Provisional limits: 8 MB per file, 5 million UTF-16 text units, 20,000 cues. Unicode characters may use more than one text unit.
Choose subtitles to begin. Nothing is automatically saved.
Cues
On a cue: ↑ / ↓ moves between matches; Home / End moves to the first / last match; Enter opens the editor. Check boxes mark cues for timing shifts.
Selected cue
Check with video
Optional. Your browser must support the codec. No transcription or upload.
Plain source-text preview; imported styling and regions are preserved in WebVTT exports, not rendered here.
Shift cue times
Use a negative offset to move captions earlier. A shift that creates negative times is rejected; nothing is clamped.
Document inspection
Reading checks
Adjust these review thresholds for your audience and language. They do not change subtitles or block export, and do not certify accessibility or platform delivery.
Counts base-text graphemes where supported (otherwise Unicode code points), including spaces but excluding line breaks, supported tags, voice labels and ruby readings. Unsupported text is flagged as unmeasured. Starting values are informed by English publishing guidance; other languages and audiences need different choices.
Before you export
Review format changes before downloading. WebVTT retains supported identifiers, settings and metadata; SRT and transcript exports have different limits. Video previews show literal cue text, without imported styling or regions.
Are my subtitles or video uploaded?
Editing runs on this device. Files and drafts are not automatically saved. Download your work before closing the tab. Local editor resources load from this website.
What can I open?
SRT or WebVTT text: up to 8 MB, five million UTF-16 text units and 20,000 cues. WebVTT requires UTF-8. Browser memory, video codecs and device performance can limit a session. Reading checks are adjustable guidance, not a delivery certification.
Does the preview reproduce every caption style?
No. It is a plain source-text timing preview. Unknown markup remains literal and is flagged for review. CSS grammar, language-registry validity and complete WebVTT rendering are not certified. Inspect your final export in its intended player.