Format guide
What is WOFF?
Web Open Font Format is Web Open Font Format 1.0 — a compressed font package for websites, created by Mozilla / W3C (2012). WOFF wraps TTF/OTF data with compression for CSS @font-face. Prefer WOFF2 today for smaller files, but WOFF remains a useful fallback in some pipelines.
WOFF format specifications
- Full name
- Web Open Font Format
- Kind
- font
- File extension
- .woff
- MIME type
- font/woff
- Developer / standard
- Mozilla / W3C · 2012
- Compression
- zlib
- 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
- Typically smaller than raw TTF/OTF
- Browser support
- Excellent
- Compatibility
- Works with CSS @font-face in browsers; not meant for OS font installation — keep TTF/OTF for desktop installs
WOFF compression & quality
WOFF compression: zlib. Lossless (or non-destructive packaging) keeps reconstructable data — size savings come from packing efficiency, not throwing detail away. Typical size profile: Typically smaller than raw TTF/OTF. Quality note: Lossless outlines with container compression
Quality: Lossless outlines with container compression
Typical size: Typically smaller than raw TTF/OTF
Transparency & animation
WOFF does not support an alpha channel. Convert to PNG, WebP, AVIF, or SVG when you need transparent backgrounds.
WOFF is a still-media or non-animated format in typical use. Use GIF, APNG, video, or animated WebP when you need motion.
WOFF metadata
Name tables, license/meta fields, and designer copyright strings live inside the font; web formats may include metadata blocks.
Best use cases for WOFF
- Web font fallback stacks
- Older @font-face pipelines
- Licensed web embedding
- Converting desktop fonts for the browser
When to avoid WOFF
- Desktop OS font installation (use TTF/OTF)
- Ignoring font licenses
- Preferring WOFF over WOFF2 on modern-only sites
- App binary embedding without subsetting
Advantages
- Built for the web
- Compressed vs raw TTF
- W3C lineage
- Works with @font-face
Disadvantages
- Larger than WOFF2
- Not for OS install workflows
- License metadata still matters
- Obsolete as the primary modern choice
Compatibility
Works with CSS @font-face in browsers; not meant for OS font installation — keep TTF/OTF for desktop installs
Browsers: Excellent
Software support
- Format Convertly
- Web build tools
Device support
- Desktop and mobile browsers
- Modern desktops
- Phones and tablets with compatible apps
How to open WOFF
Load via CSS in a browser; inspect with font tools — not a double-click install font on most OS setups.
How to convert WOFF
Convert between TTF, OTF, WOFF, and WOFF2 in Format Convertly for licensed web stacks, privately in-browser so font files never upload.
Popular WOFF conversions
Convert to WOFF
Incoming conversions strengthen the WOFF cluster — e.g. JPG → WOFF, PNG → WOFF.
Best format guides featuring WOFF
Decision pages that cite WOFF — the next hop after a vs comparison.
Related formats
WOFF tools
Tools extend the format graph beyond one-off conversion — compression, metadata, and utilities for real workflows.
WOFF FAQ
What is a WOFF file?
WOFF is Web Open Font Format 1.0 — a compressed font package for websites. WOFF wraps TTF/OTF data with compression for CSS @font-face. Prefer WOFF2 today for smaller files, but WOFF remains a useful fallback in some pipelines.
Is WOFF lossy or lossless?
WOFF is typically lossless or non-destructive in common use (zlib).
Does WOFF support transparency?
WOFF does not support an alpha channel. Convert to PNG, WebP, AVIF, or SVG when you need transparent backgrounds.
How do I open a WOFF file?
Load via CSS in a browser; inspect with font tools — not a double-click install font on most OS setups.
How do I convert WOFF privately?
Convert between TTF, OTF, WOFF, and WOFF2 in Format Convertly for licensed web stacks, privately in-browser so font files never upload. Format Convertly keeps processing in your browser so files are not uploaded to a conversion server.
Are my WOFF files uploaded on Format Convertly?
No. WOFF conversion runs in your browser. Files are not sent to Format Convertly servers for processing.