Free, instant, and entirely in your browser — your subtitle file is never uploaded.
MicroDVD counts frames, not seconds — this has to match the video.
WebVTT is SRT rebuilt for the web: the same cue structure, a WEBVTT header line, a dot instead of a comma before the milliseconds, and optional positioning settings after the timestamp. It is the only subtitle format HTML5 video natively understands.
ASS is a typesetting language that happens to carry subtitles. Named styles, exact positioning, rotation, fades, karaoke timing and vector drawing all live in the file, split across a [Script Info], a styles and an [Events] section.
Usually this means a translation is moving from distribution back into production. The VTT was made to be served to a browser — flat, simple, designed for playback — and ASS is where it goes to be worked on: styles per speaker, signs placed over the picture, timing refined frame by frame in Aegisub. Any positioning cues the VTT carried are dropped rather than translated, because VTT and ASS describe position in incompatible ways and a wrong position is worse than none.
You want ASS because you are about to typeset, not merely translate. Going into ASS is what opens the door to named styles, exact positioning, fades and karaoke timing in an editor like Aegisub. The conversion does not create any of that — it gives you a clean file with one default style, ready for the work to begin.
The target format can do far more than the source ever could, but a conversion cannot invent design that was never there. What you get is a well-formed file with a single default style — correct, playable, and ready to be styled properly in an editor like Aegisub. The gain is real but it is potential: the capability is now available to you, not already used.
No. The conversion runs in your browser using JavaScript — your VTT file is read from disk, converted in memory and handed back as a download. Nothing is transmitted, so there is nothing for us to store or delete. You can disconnect from the internet after this page loads and the conversion still works.
Usually this means a translation is moving from distribution back into production. The VTT was made to be served to a browser — flat, simple, designed for playback — and ASS is where it goes to be worked on: styles per speaker, signs placed over the picture, timing refined frame by frame in Aegisub. Any positioning cues the VTT carried are dropped rather than translated, because VTT and ASS describe position in incompatible ways and a wrong position is worse than none.
The page checks before it converts. Subtitle formats are identified by what is inside the file rather than by the extension — which matters, because .sub alone is used by three unrelated formats. If you hand this page something that is not VTT, it says so and points you at the all-format converter instead of producing a broken file.