VTT to ASS Converter

The VTT to ASS Converter parses the WebVTT captions you paste into the VTT Content box and writes an Advanced SubStation Alpha file complete with the script info, style and events sections that ASS requires. Every VTT cue becomes a Dialogue line with ASS-style timing, and the result downloads as a .ass file you can open in Aegisub or any subtitle editor that understands the format.

WebVTT is the format of the web player: simple, unstyled and perfectly adequate for HTML5 video. ASS is the format of the editor: it supports fonts, colours, outlines, precise positioning, fades and karaoke timing. Fansubbers, motion designers, anime and gaming localisers, and anyone who has to place a caption away from burned-in on-screen text need to move from one to the other, and hand-rewriting a few hundred cues into Dialogue lines is nobody's idea of a good afternoon. That is the job of this vtt to ass converter.

Technically, the VTT parser handles the details that trip up naive conversions: the WEBVTT header, NOTE comment blocks that must be skipped rather than treated as captions, optional cue identifiers before the timing line, and the dot decimal separator VTT uses where SRT uses a comma. Timings are held internally as milliseconds and re-emitted in the ASS centisecond form, H:MM:SS.cc. The Shift by (ms, +/-) field adds its value to both the start and end of every cue before writing, so a track that runs consistently early or late is corrected in the same pass. The output carries a single sensible default style, which is the starting point you then refine in an ASS editor.

Conversion is entirely client side - nothing is uploaded - and even a full episode's worth of cues converts instantly.

• Proper WebVTT parsing: the WEBVTT header, NOTE comment blocks and optional cue identifiers are recognised and handled, so comments never leak into your subtitles as stray captions.
• Dot timestamps understood: VTT's 00:00:04.500 form is read correctly and converted to the centisecond precision ASS Dialogue lines use.
• Complete ASS document: the output includes the script info, style definition and events sections rather than a loose list of Dialogue lines, so editors open it without complaint.
• Default style to build on: a single readable default style is written for every cue, giving you one place to change font, size, colour and margins for the whole file.
• Built-in resync: the Shift by (ms, +/-) field offsets every cue in one pass, so a file that starts a second late does not need a separate correction tool.
• Line breaks preserved: multi-line VTT cues keep their break structure in the ASS output instead of collapsing into one long line.
• Private and instant: the convert vtt to ass online workflow runs locally in your browser with no upload, account or file limit.

1. Paste the whole WebVTT file - including the WEBVTT line at the top - into the VTT Content box, or click Load sample to try the tool with example cues.
2. Leave Shift by (ms, +/-) at zero if the VTT is already in sync with your video.
3. If the captions run late, enter a negative value such as -800 in Shift by (ms, +/-); if they run early, enter a positive one.
4. Press Run to generate the ASS document, which appears immediately in the output panel.
5. Look at the Style line near the top of the result to see the default that has been applied, and check that the first Dialogue line's timing matches the first cue you expected.
6. Click Copy, or Download to save the file with the .ass extension.
7. Open the saved .ass in Aegisub or a similar editor to set your real font, colours, outline and positioning, then export or mux it with the video.

Example 1 - a plain cue with a comment above it. The NOTE block is skipped and only the caption is converted.

Input (VTT):
WEBVTT

NOTE checked against the mix on 12 May

00:00:01.000 --> 00:00:04.000
Welcome to the harbour tour.

Output (ASS):
Dialogue: 0,0:00:01.00,0:00:04.00,Default,,0,0,0,,Welcome to the harbour tour.

The dot timestamps become ASS centisecond timings, and the cue is attached to the Default style defined in the file's header.

Example 2 - shifting a late track. With -1000 in Shift by (ms, +/-), the same cue is written as Dialogue: 0,0:00:00.00,0:00:03.00,Default,,0,0,0,,Welcome to the harbour tour. Every cue moves by the same amount, so the pacing between captions is untouched while the file as a whole lines up with the picture.

• Opens up real styling: once your captions are in ASS you can set fonts, colours, outlines and positions that WebVTT simply cannot express.
• Saves a full retyping pass: hundreds of Dialogue lines are generated in one click, which is hours reclaimed on every episode.
• Avoids caption clashes: being able to reposition subtitles in an ASS editor means text no longer sits on top of burned-in signage or lower thirds.
• Corrects sync while converting: a single offset entry fixes a consistently late or early track without a second tool or a second export.
• Keeps comments out of the subtitles: proper NOTE handling prevents production notes from ever appearing on screen in front of an audience.
• Nothing leaves your machine: unreleased episodes and client material stay local, so there is no upload policy to clear before you start.