Convert ASS
to IMSC
Drop in a .ass (Advanced SubStation Alpha) file, get a clean .xml (Internet Media Subtitles and Captions) back. Internet Media Subtitles and Captions is the modern W3C streaming profile of TTML used by Netflix, Apple TV, and most streaming services. The conversion runs entirely in your browser — your captions never leave the page.
Frequently asked
Why convert ASS to IMSC?+
Advanced SubStation Alpha is the heavily-styled subtitle format used by Aegisub and the fansub community. Internet Media Subtitles and Captions is built for streaming delivery to HLS / DASH manifests and modern OTT ingest. Converting lets you take a file produced for one workflow and use it in the other without re-typing or re-timing anything.
Is timing preserved exactly?+
Yes. The converter only re-encodes the file structure — start and end times round-trip to within one millisecond.
Does any styling survive the conversion?+
Most styling drops in this direction. ASS supports inline styling and IMSC doesn't, so override codes, cue tags, and positioning attributes are stripped. Timing and text always survive.
Does this run on a server?+
No. The conversion is pure JavaScript running in your browser — files never upload anywhere. Works offline once the page is loaded.