Standard or regulation

WebVTT: The Web Video Text Tracks Format (Editor's Draft)

W3C Timed Text Working Group, W3C, 2026

Read on October 16, 2026

What it is: The W3C specification of WebVTT, the plain-text format browsers use for captions, subtitles and other timed text tracks.
How much weight it carries: The defining specification, so authoritative for the format. It is a Candidate Recommendation Draft and may change in detail.

Facts taken from this source

The W3C says the SRT file format was used as the basis for the WebVTT text track format.
“whose SRT file format was used as the basis for the WebVTT text track file format” (Acknowledgements)
A WebVTT file must be UTF-8 text labeled with the MIME type text/vtt.
“A WebVTT file must consist of a WebVTT file body encoded as UTF-8 and labeled with the MIME type text/vtt” (4.1 WebVTT file structure)
The W3C WebVTT specification says the main use for WebVTT files is captioning or subtitling video content.
“The main use for WebVTT files is captioning or subtitling video content.” (Example WebVTT file (non-normative section))
The W3C WebVTT specification's sample caption file for an interview begins with the word WEBVTT, followed by timed cues.
“Here is a sample file that captions an interview: WEBVTT 00:11.000 --> 00:13.000” (Example WebVTT file (non-normative section))
The W3C specification says a WebVTT file consists of a sequence of text segments, each associated with a time interval called a cue.
“a WebVTT file in general consists of a sequence of text segments associated with a time-interval, called a cue” (1. Introduction)
In WebVTT, the thousandths of a second in a timestamp follow a full stop character.
“A U+002E FULL STOP character (.). Three ASCII digits” (Timestamp syntax)

Standard or regulation

W3C Timed Text Working Group, W3C, 2026

Read on October 16, 2026

What it is: The W3C specification of WebVTT, the plain-text format browsers use for captions, subtitles and other timed text tracks.
How much weight it carries: The defining specification, so authoritative for the format. It is a Candidate Recommendation Draft and may change in detail.

The W3C says the SRT file format was used as the basis for the WebVTT text track format.
“whose SRT file format was used as the basis for the WebVTT text track file format” (Acknowledgements)
A WebVTT file must be UTF-8 text labeled with the MIME type text/vtt.
“A WebVTT file must consist of a WebVTT file body encoded as UTF-8 and labeled with the MIME type text/vtt” (4.1 WebVTT file structure)
The W3C WebVTT specification says the main use for WebVTT files is captioning or subtitling video content.
“The main use for WebVTT files is captioning or subtitling video content.” (Example WebVTT file (non-normative section))
The W3C WebVTT specification's sample caption file for an interview begins with the word WEBVTT, followed by timed cues.
“Here is a sample file that captions an interview: WEBVTT 00:11.000 --> 00:13.000” (Example WebVTT file (non-normative section))
The W3C specification says a WebVTT file consists of a sequence of text segments, each associated with a time interval called a cue.
“a WebVTT file in general consists of a sequence of text segments associated with a time-interval, called a cue” (1. Introduction)
In WebVTT, the thousandths of a second in a timestamp follow a full stop character.
“A U+002E FULL STOP character (.). Three ASCII digits” (Timestamp syntax)