Subtitles & Closed Captions: SRT, VTT & ASS
Synchronizing text transcriptions with video streams and streaming platforms.
Files are processed locally in your browser with WebAssembly and HTML5 APIs. They never leave your device, so there are no server uploads or third-party file storage.
Start converting immediately on your own device - no upload wait, no download queue, and no throttling by a remote server.
Use every available tool without creating an account, paying for a plan, or hitting an artificial file-size limit. Convert as often as your browser and device can handle.
Format Comparison & Technical Specifications
| Output Format | MIME Type | Specification | Type |
|---|---|---|---|
| SRT SubRip Text | text/plain | SUBRIP-SPEC | SubRip Timed Caption File |
| VTT WebVTT Caption | text/vtt | W3C-WEBVTT | Web Video Text Tracks |
| ASS Advanced SubStation Alpha | text/x-ssa | ASS-SPECS | Styled SSA Subtitle Script |
| SUB MicroDVD Subtitle | text/plain | SUBRIP-SPEC | MicroDVD Frame Subtitle |
| TXT Plain Text Transcript | text/plain | RFC-4180-CSV | Unformatted Subtitle Transcript |
Technical Specifications & Codec Breakdown
SRT vs. WebVTT: The Web Video Standard
SRT is the classic, simple subtitle format supported by almost every media player. WebVTT is the modern W3C web standard: it supports styling (colors, font sizes, positioning), making it the required format for HTML5 video players and streaming platforms.
Timestamp Drift & Frame Rate Mismatches
If video audio and captions slowly drift out of sync over a 2-hour movie, it is usually caused by a frame rate mismatch (e.g., 23.976 fps film vs. 25 fps PAL video). Converting subtitle timecodes ensures captions match the exact audio cues.
0 bytes uploaded to external servers. All processing occurred locally in your browser sandbox.