VTT to ASS Converter
Drop a WebVTT file, get an ASS ready for styling in Aegisub or hard-subbing with ffmpeg.
Drop your VTT file here
Converts to .ass — stays on your device
Why convert VTT to ASS?
- Restyling YouTube auto-captions downloaded as VTT in Aegisub — add a branded font, reposition, or convert to karaoke for a music video.
- Taking HTML5 video captions from a webinar platform (Livestorm, Demio) and moving them into a fansub-style workflow.
- Prepping subtitles from a modern web source for hard-subbing into an MP4 with ffmpeg's ASS burn-in (which offers far richer styling than SRT burn-in).
- Starting a karaoke video project from the VTT lyric file a lyrics service exported — ASS is the format every karaoke workflow expects.
- Migrating captions from a Vimeo or Wistia download to an Aegisub-based translation team's working format.
- Building a styled ASS template once, then converting every VTT you receive into ASS that inherits the template's look.
How our converter works
Your WebVTT file is parsed into a cue list — the 'WEBVTT' header, style blocks, and cue settings are read but dropped (ASS doesn't use them the same way). Each cue becomes an ASS Dialogue line under a default style (Arial 20pt, white on black outline). Timestamps are re-emitted in ASS's centisecond format. Open the output in Aegisub and all of ASS's styling power is available. Everything runs locally — VTT captions from paid courses, client webinars, and embargoed content stay on your device.
VTT vs ASS — what's the difference?
| Feature | VTT | ASS |
|---|---|---|
| Structure | Plain cues with optional settings | Sections — Script Info, Styles, Events |
| Styling | CSS-like, limited | Full — fonts, colors, positions, karaoke, transforms |
| Target use | Web video, HTML5 <track> | Desktop fansub, hard-subbing, karaoke |
| Timestamp precision | Milliseconds | Centiseconds |
| Best for | Online delivery | Advanced authoring, restyling, burn-in |
Frequently asked questions
Will VTT cue positioning carry over?
No. VTT's positioning, alignment, and style classes don't translate into ASS style entries automatically. All cues appear in ASS's default style — you restyle in Aegisub after import.
Does the WebVTT header get preserved?
The 'WEBVTT' header is parsed and dropped — ASS doesn't use it. The output begins with an ASS Script Info section with metadata identifying FormatFixer as the creator.
What styling does the ASS default to?
Arial 20pt, white text with a black outline, centered bottom — the Aegisub default. Everything from there is yours to customize.
Is this useful for hard-subbing?
Yes. ASS burn-in via `ffmpeg -vf subtitles=file.ass` gives you font, color, positioning, and transform control that SRT or VTT can't match. Going VTT → ASS → ffmpeg is a common path when web captions need to be styled before burn-in.
Are my caption files uploaded?
No. The conversion runs entirely in your browser — unreleased course captions, NDA-bound client work, and embargoed content never leave your device.
Can I batch-convert several VTTs at once?
Yes. Drop multiple VTT files and each becomes its own .ass. For four or more, the output is packaged as a ZIP download.
About the VTT format
WebVTT (Web Video Text Tracks) is the W3C's web-native caption format — the format HTML5 <track>, YouTube, and every browser understand. It supports positioning and simple styling via cue settings and style blocks, but its design target is web delivery, not advanced authoring. ASS (Advanced SubStation Alpha) occupies the opposite end: a rich, fansub-community-built format handled by Aegisub and desktop players like mpv and VLC, with precise control over every visual aspect of a caption. Converting VTT to ASS is the standard move when web-sourced captions need styling beyond what the web platform offers — or when a VTT is being prepped for ffmpeg hard-subbing, where ASS gives you substantially more control than VTT or SRT can.