Fact · Transcription
A WebVTT file must be UTF-8 text labeled with the MIME type text/vtt.
Checked against its source on October 17, 2026
In the source's own words
“A WebVTT file must consist of a WebVTT file body encoded as UTF-8 and labeled with the MIME type text/vtt”
WebVTT: The Web Video Text Tracks Format (Editor's Draft), W3C Timed Text Working Group, W3C, 2026, 4.1 WebVTT file structure.
Open the original- What it measures
- A plain text editor can write a valid WebVTT file, as long as it saves UTF-8 text and begins with the WEBVTT header.
- What it does not show
- Read from the W3C editor's draft, which can change before the specification is final. Check the current version before relying on new features.