About VTT Files
WebVTT Subtitle
WebVTT (Web Video Text Tracks) is the standard subtitle format for HTML5 video.
Family
Documents & Text
Extension
.vtt
MIME Type
text/vtt
Can Use As
HOW VTT
CAME TO BE.
WebVTT — Web Video Text Tracks — was drafted by the WHATWG in 2010 as the native subtitle format for HTML5 <video>. Its design borrows heavily from SRT (same block-based structure, similar timecode) but adds the features web video needed: CSS styling, positioning cues, chapter markers, and a strict requirement to be UTF-8.
The W3C candidated the spec in 2019 and it is now the standard subtitle format for HTML5 <video>. Every streaming platform that targets the open web (YouTube, Vimeo, BBC iPlayer, Coursera) serves subtitles as WebVTT. It has not replaced SRT in torrents or desktop players but completely dominates in-browser video.
CURIOSITIES &
TRIVIA.
WebVTT is SRT's web-native evolution: same structure, plus CSS styling, positioning, and chapter tracks.
The timecode separator is "." (dot) in WebVTT and "," (comma) in SRT — a one-byte difference.
Every WebVTT file must start with the literal header "WEBVTT" — miss it and browsers refuse to load it.
YouTube auto-generated captions are served as WebVTT with embedded timing precision down to 1 ms.
WebVTT can carry chapter markers — the <video> element exposes them as navigable cue points.
STRENGTHS &
LIMITATIONS.
Strengths
- Native HTML5 <video> support — no JavaScript needed.
- CSS styling, positioning, and layout control.
- Strict UTF-8 eliminates encoding guesswork.
- Supports chapters, metadata tracks, and descriptions for accessibility.
- W3C standardized — long-term stability guaranteed.
Limitations
- Slightly more verbose than SRT.
- Tooling in desktop players lags behind SRT.
- Browser CSS styling of cues varies in subtle ways.
- Conversion from SRT is easy but not always clean for edge cases.
Typical Sizes & Weights
1-hour TV episode
40-100 KB
2-hour movie with styled cues
80-200 KB
Technical Specifications
- MIME type
- text/vtt
- Extension
- .vtt
- Standard
- W3C WebVTT Recommendation
- Timecode format
- HH:MM:SS.mmm --> HH:MM:SS.mmm
- Encoding
- UTF-8 (required, no BOM)
CONVERT FROM
VTT
CONVERT TO
VTT
Common Use Cases
Web video captions, accessibility
Related Formats
Popular comparisons
VTT vs SRT
Differences, file size, and when to choose each format.
VTT vs PDF
Differences, file size, and when to choose each format.
VTT vs DOCX
Differences, file size, and when to choose each format.
VTT vs ODT
Differences, file size, and when to choose each format.
VTT vs TXT
Differences, file size, and when to choose each format.
VTT vs MD
Differences, file size, and when to choose each format.
Popular VTT conversions
The most-requested destinations when starting from VTT.
Frequently Asked Questions about VTT
Frequently Asked Questions
VTT (WebVTT Subtitle) is a document format used to store paginated text, with optional formatting, tables, images, hyperlinks, headers and footers. It sits in the documents & text family and is typically associated with a specific office suite or publishing pipeline that defined the format and ships the canonical reader.
Modern office suites — Microsoft Word, Google Docs, LibreOffice Writer, Apple Pages — open most VTT files with reasonable fidelity. If your installed software does not support VTT, convert to DOCX or PDF first using KaijuConverter; both open in virtually every reader, including free online viewers.
Upload the VTT to KaijuConverter and pick DOCX, PDF, ODT, RTF, HTML, Markdown, or plain text. Our pipeline runs LibreOffice headlessly plus pandoc for text formats — the same engines behind professional document pipelines. Styles, tables, images, and hyperlinks survive the conversion intact.
Yes, to a high degree. Standard fonts, headings, lists, tables, images, hyperlinks and page structure transfer cleanly. Custom fonts substitute to the closest match if not embedded; obscure layout features unique to VTT (frames, legacy macros) may flatten to static content in the target format.