The subtitle format built for HTML5 video - what a browser loads into a track element. It's SRT with a header, a full stop instead of a comma in the timestamps, and optional positioning and styling that most people never touch.

Every conversion below runs in this page, on your own machine. Nothing is uploaded, there is no queue, and there is no account to make. Pick a target format, or just drop a WebVTT file above and choose afterwards.