WebVTT support in browsers

Feature Chrome/Opera Firefox Internet Explorer Safari
Required Header WEBVTT WEBVTT WEBVTT FILE WEBVTT
File MIME Type sniffing sniffing 'text/vtt' sniffing
Menu in video controls to select tracks CC button
JavaScript TextTrack API
Rendering of text-only captions & subtitles
Cue styling with ::cue and ::cue()
Cue markup incl. Timestamps
Vertical Cue setting ✔ (buggy)
Line, Align, Position, Size Cue settings
Comments (NOTE)
Regions Behind Flag Behind Flag
Rendering of text descriptions With extension
Rendering of chapters

Converting SRT files to WebVTT files

Cut and paste SRT file into text entry box:

Source code at Github.

Thanks to David Desmeurs for his contribution.