Format guide
What is VTT?
VTT file format is WebVTT — the web-native text track format for HTML5 video captions and subtitles, created by W3C (2010s). VTT adds web-friendly captions with optional styling cues for browsers. Use it for <track> elements; keep SRT around when collaborating with desktop subtitle tools that still default to SubRip.
VTT format specifications
- Full name
- VTT file format
- Kind
- structured data
- File extension
- .vtt
- MIME type
- application/octet-stream
- Developer / standard
- W3C · 2010s
- Compression
- none or container
- Quality model
- Lossless / not lossy
- Container
- No / single bitstream typical
- Common codecs
- —
- Technical sources
- —
- Transparency
- Not supported
- Animation
- No (still / non-animated typical use)
- Typical size
- Tiny
- Browser support
- Designed for HTML5 video elements
- Compatibility
- Modern browsers for HTML5 tracks; editors via conversion
VTT compression & quality
VTT compression: none or container. Lossless (or non-destructive packaging) keeps reconstructable data — size savings come from packing efficiency, not throwing detail away. Typical size profile: Tiny. Quality note: Text cues with more web styling hooks than SRT
Quality: Text cues with more web styling hooks than SRT
Typical size: Tiny
Transparency & animation
VTT does not support an alpha channel. Convert to PNG, WebP, AVIF, or SVG when you need transparent backgrounds.
VTT is a still-media or non-animated format in typical use. Use GIF, APNG, video, or animated WebP when you need motion.
VTT metadata
Usually none beyond encoding/BOM — structure is the content. Comments allowed in YAML/TOML.
Best use cases for VTT
- HTML5 video accessibility tracks
- Browser-based course players
- Web caption delivery
- Modern streaming web apps
When to avoid VTT
- Legacy desktop tools that only ingest SRT
- Assuming identical styling across all browsers
- Broadcast sidecar formats
- Burned-in captions (rasterize/encode instead)
Advantages
- Web native
- Supports voice/accessibility metadata hooks
- Works with <track>
- Still human-editable text
Disadvantages
- Some desktop tools prefer SRT
- Styling support varies
- Timing still easy to get wrong
- Not a burned-in solution
Compatibility
Modern browsers for HTML5 tracks; editors via conversion
Browsers: Designed for HTML5 video elements
Software support
- Browsers
- Subtitle Edit
- ffmpeg workflows
- Format Convertly
Device support
- Web video on desktop and mobile browsers
- Modern desktops
- Phones and tablets with compatible apps
How to open VTT
Inspect in a text editor; test in a browser with a video element and <track src=".vtt">.
How to convert VTT
Convert VTT↔SRT in Format Convertly when your editor or player expects the other subtitle format — private and local.
Popular VTT conversions
Convert to VTT
Incoming conversions strengthen the VTT cluster — e.g. JPG → VTT, PNG → VTT.
Related formats
VTT tools
Tools extend the format graph beyond one-off conversion — compression, metadata, and utilities for real workflows.
VTT FAQ
What is a VTT file?
VTT is WebVTT — the web-native text track format for HTML5 video captions and subtitles. VTT adds web-friendly captions with optional styling cues for browsers. Use it for <track> elements; keep SRT around when collaborating with desktop subtitle tools that still default to SubRip.
Is VTT lossy or lossless?
VTT is typically lossless or non-destructive in common use (none or container).
Does VTT support transparency?
VTT does not support an alpha channel. Convert to PNG, WebP, AVIF, or SVG when you need transparent backgrounds.
How do I open a VTT file?
Inspect in a text editor; test in a browser with a video element and <track src=".vtt">.
How do I convert VTT privately?
Convert VTT↔SRT in Format Convertly when your editor or player expects the other subtitle format — private and local. Format Convertly keeps processing in your browser so files are not uploaded to a conversion server.
Are my VTT files uploaded on Format Convertly?
No. VTT conversion runs in your browser. Files are not sent to Format Convertly servers for processing.