What is a VTT file?
VTT (WebVTT) is the W3C standard subtitle format for HTML5 <video> elements. Browsers use VTT to render caption tracks; it's almost identical to SRT but adds a 'WEBVTT' header and dot-separated timestamps.
Detail
WebVTT (Web Video Text Tracks) was standardized by the W3C in 2013 as the native caption format for HTML5 video. A VTT file is a plain-text file with a 'WEBVTT' header followed by cue blocks — each cue has a start and end timestamp (HH:MM:SS.mmm using dots, not commas like SRT), and the caption text. Browsers render VTT captions via the <track> element inside <video>. Beyond the header and timestamp punctuation, VTT adds features SRT lacks: cue positioning (align, line, position CSS properties), voice spans (<v Speaker>), and chapter markers. For most practical use, VTT and SRT are interchangeable — the only time you specifically need VTT is for an HTML5 web embed on your own site. Platforms like YouTube, Vimeo, Facebook, and LinkedIn all accept SRT; their backends convert to VTT internally.
| Feature | SRT | VTT |
|---|---|---|
| File header | None | WEBVTT line required |
| Timestamp separator | Comma (,) | Dot (.) |
| Cue positioning | No | Yes (CSS props) |
| HTML5 <track> support | No (browser ignores) | Yes |
| Platform compatibility | Universal | Universal |
| Styling tags | Unofficial | Official |
SRT for almost everything: video editors, YouTube, Vimeo, every major platform. VTT only when you're embedding video on a website with HTML5 <track>.
SRT (SubRip Subtitle) is a plain-text subtitle format with numbered cues and HH:MM:SS,mmm timestamps. It's the most universal subtitle format.