What is a .woff file?

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What is it

You have a .woff file — the first web-specific font format, designed to make custom fonts fast and legal to serve on the web. WOFF wraps TrueType or OpenType font data with zlib compression and metadata, producing files smaller and more web-appropriate than raw TTF/OTF.

WOFF was standardised in 2010 by the W3C after browser vendors agreed they needed a font format designed specifically for web delivery. It solved two problems: file size (compression reduced download times) and licensing (metadata fields let foundries embed usage restrictions). Every browser shipped WOFF support quickly, making custom web typography mainstream. Then WOFF2 arrived with Brotli compression and made WOFF the middle child.

Every browser supports WOFF, but WOFF2 is 30-50% smaller. For new projects, serve WOFF2 as the primary format and WOFF as a fallback only if you need to support very old browsers (Safari 5, Android 4). FontForge (free) converts between WOFF and other font formats. Most Google Fonts and font foundries provide WOFF alongside WOFF2 in their web font packages.

Technical details

Full Name

Web Open Font Format

MIME Type

font/woff

Developer

W3C

Magic Bytes

77 4F 46 46

Safety

What opens it

Any web browser

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FontForge

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FAQ

Should I use WOFF or WOFF2?

WOFF2. It's 30-50% smaller thanks to Brotli compression and supported by every modern browser. Include WOFF as a fallback only if you need to support browsers older than 2015.

What's the difference between WOFF and TTF for web use?

WOFF is compressed and designed for web delivery — smaller files, faster page loads. TTF is uncompressed and designed for desktop installation. Always serve WOFF or WOFF2 on the web, not raw TTF.

Related formats

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