Read the source
Choose an original subtitle file to check its encoding, or paste text for a structure and timing check.
Make every line land
Subtitle Repair & Sync
Find subtitle errors, put the timing back in place, and review every change before you export. Your original stays untouched.
Files stay on your deviceReview before exportSRT · WebVTT
A better subtitle file starts here.
Drop one SRT or VTT file, or paste your subtitle text.
One file · Up to 5 MiB · 20,000 cues
Local processing. No upload, no AI key, no changes to your original file.
Checking subtitles locally…
01 / Source
Keep the original in view
Encoding selection reads the original file bytes. Pasted or edited text is already decoded.
02 / Inspect & adjust
Small fixes. Clear decisions.
Choose your repairs
Start with safe numbering. Changes that can alter content or timing are your choice.
Overlaps may be intentional. Timing repairs do not verify what is said in the video.
Positive = later. Negative = earlier. Negative result times are blocked, not silently clipped.
Pick two matching moments, far apart. Enter seconds, with decimals if needed. This only corrects linear drift.
Positions refer to the original file order, not its printed cue numbers. Leave the end blank for all remaining cues.
Check results
Errors must be resolved before subtitle export. Warnings need review, but are not always mistakes.
What will change?
03 / Review & export
A new file. Nothing overwritten.
This conversion cannot keep these WebVTT features:
The JSON report includes cue positions, findings and changes, not the full subtitle dialogue. Subtitle downloads use the site's shared daily allowance.
Check it against your video
Optional, local, plain-text preview. Browser-supported codecs only; no video conversion.
Up to 512 MiB · Never uploaded
A clear workflow
From a broken file to a reviewed result.
Choose, then preview
Review findings, select only the repairs you want, and compare the proposed changes before downloading.
Export a separate copy
Download UTF-8 SRT or WebVTT. Check the file in its destination player or platform; the original remains unchanged.
Built for real files
Repair with context, not guesswork.
Understand what your subtitle file contains and decide which changes are appropriate for your video.
Your dialogue stays yours
No translation or rewriting. Subtitle content is displayed as text, and files are processed on your device.
Destructive fixes are opt-in
Empty cues, reversed times and overlaps may need different decisions. Review the options instead of accepting a hidden one-click cleanup.
Format limits stay visible
Unsupported or ambiguous input is reported. WebVTT-to-SRT feature losses require approval rather than disappearing unnoticed.
Good to know
Make your subtitles land on time.
Keep the original, compare familiar moments, and choose the smallest change that solves the problem.
- A constant delay needs an offset. A steadily growing delay may need two-point calibration. Different edits or missing scenes need manual work.
- For garbled Chinese, load the original file and compare encoding choices. Copying already damaged text cannot restore lost bytes.
- Overlapping captions can represent two speakers. Review the video before shortening or removing a cue.
- Keep WebVTT when you need its settings or metadata. The local video preview checks timing with plain text, not all subtitle styling.
Before you export
Questions, answered.
What can this subtitle repair tool fix?
It checks supported SRT and WebVTT files for numbering, timecode, empty-cue and timing problems. You can normalize numbering, adjust timing and choose specific repairs. Unrecognized or ambiguous content is reported rather than silently discarded.
Can it automatically synchronize subtitles with speech?
No. Use a known time offset, or enter two matching source and video times to correct linear drift. This tool does not listen to audio, transcribe speech, translate dialogue or repair missing scenes.
Can I fix Chinese subtitle encoding?
For an original file, automatic detection checks Unicode byte-order marks and valid UTF-8. If needed, choose GB18030, Big5, UTF-16 or Windows-1252 and inspect the decoded text. Characters already lost or replaced cannot reliably be recovered.
Will repairs overwrite my original subtitles?
No. The original file is not changed. You review a separate result and download a new UTF-8 file. Sorting, dropping empty cues, swapping reversed times and trimming overlaps are optional and off by default.
Does converting WebVTT to SRT preserve every feature?
No. SRT cannot preserve all WebVTT identifiers, settings, metadata and markup. The tool lists detected conversion losses and requires your explicit approval before a lossy export. Prefer WebVTT when you need its features.
Are subtitles and videos uploaded?
No. This tool reads selected files locally in your browser. Subtitle text, filenames and video content are not sent to ToolKnit or an AI provider. Loading the website, shared components and existing site analytics can use the network.
What limits and preview formats are supported?
Choose one subtitle file up to 5 MiB and 20,000 cues. Local video preview is optional, limited to 512 MiB, and depends on codecs your browser supports. It displays plain text for timing checks, not an exact player or platform rendering.