Text Toolbox
Text Local only
Subtitle Editor & Format Converter
Local subtitle workflowEdit, synchronize, validate, preview and convert SRT, WebVTT, ASS, LRC, SBV and TTML locally.
Edit and synchronize captions locally
Open SRT, WebVTT, ASS, LRC, SBV or TTML, refine timing against optional local media, run caption QA and export without an upload.
Captions and media stay on this device
Parsing, editing, preview, waveform and exports run in the browser. The tool does not transcribe, translate or contact a media service.
How to use it
- 01
Open subtitles or start blank
Detect and normalize six common caption formats locally, including UTF-8 and UTF-16 text.
- 02
Edit and synchronize
Edit cue text and times, use the visual timeline and optional local media, then shift, scale, convert frame rate or repair gaps.
- 03
Review and export
Check overlap, speed and line-quality findings, preview conversion loss, and export subtitles, CSV or redacted evidence.
Frequently asked questions
Are subtitles or media uploaded?
No. Text parsing, media preview and supported waveform decoding happen in the browser with temporary local object URLs.
Which conversions can lose information?
SRT and LRC cannot preserve every WebVTT setting, ASS style or TTML structure. The editor warns before a target format drops positioning, styling or explicit end times.
Does it translate or transcribe audio?
No. The editor provides deterministic editing, synchronization and QA without sending media to speech-recognition or translation services.
Does it follow WebVTT?
The parser and serializer follow the W3C model for common cue syntax and report unsupported or malformed evidence. Browser rendering can still vary for advanced styling.
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