| Format | Input | Output |
|---|---|---|
| SRT | ✅ | ✅ |
| VTT (WebVTT) | ✅ | ✅ |
| ASS | ✅ | ✅ |
| SBV | ✅ | ✅ |
| SUB | ✅ | ✅ |
| STL | ✅ | ✅ |
| TXT (plain text) | — | ✅ |
SRT vs. WebVTT
WebVTT (.vtt) is the browser-native caption standard — what <track> elements and most video players expect. SRT (SubRip) is the de facto interchange format in editing tools and legacy pipelines. This SRT to VTT API (and VTT to SRT) is the bridge between the two, with ASS support for styled subtitles when you need it.