What is WOFF? Web Open Font Format Explained
A W3C web font format that wraps and compresses TrueType or OpenType fonts.
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What is WOFF?
WOFF (Web Open Font Format) is a font packaging format designed for use on the web and published as a W3C Recommendation in December 2012. It is essentially a compressed wrapper around existing SFNT-based fonts such as TrueType and OpenType.
A WOFF file contains the same font tables as the original TTF or OTF, but compressed (using zlib) and accompanied by optional metadata. Browsers decompress the font and use it via CSS @font-face, reducing download size compared with raw TTF/OTF files.
How WOFF Works
WOFF takes the table directory of an SFNT font, compresses each table individually with zlib, and stores them with a WOFF header plus offsets and original lengths so the browser can reconstruct the exact original font in memory.[1] An optional block can carry XML metadata such as licensing information.[1]
History and Standardization
WOFF was published as a W3C Recommendation in December 2012, giving the web a single, royalty-free web font format after the fragmentation of EOT and raw TTF/OTF linking.[2] It is registered with the media type font/woff and is loaded via the CSS @font-face rule.[4]
WOFF vs Raw Fonts
Because it wraps the same tables, a WOFF file decodes to a font identical to the source TTF or OTF, while transferring fewer bytes over the network.[3] Its per-table zlib compression is, however, less aggressive than the Brotli-based compression introduced in WOFF2.[3]
MKV Technical Specifications
WOFF vs Other Font Formats
| Feature | WOFF | WOFF2 | TTF |
|---|---|---|---|
| Type | Web font wrapper[1] | Web font wrapper | Outline font |
| Standardized by | W3C[1] | W3C | Apple / IANA |
| Compression | zlib / DEFLATE[3] | Brotli | None |
| Browser support | Universal[4] | Modern browsers | Wide |
| Best for | Broad web compatibility | Smallest web fonts | Desktop fonts |
WOFF offers the widest browser support, while WOFF2 compresses more tightly for modern browsers.
Advantages & Disadvantages
Advantages
WOFF compresses font tables with zlib, typically reducing TrueType file sizes by 40% or more for faster page loads.
All major browsers support WOFF, making it a safe baseline web font format.
WOFF wraps the original SFNT tables losslessly, so the font's outlines and features are fully retained.
The format can embed licensing and provenance metadata alongside the font.
Disadvantages
WOFF2 offers significantly better compression, so WOFF is now mostly a fallback for older browsers.
WOFF is intended for web delivery and is not used as a desktop or print font format.
Browsers must decompress the font before use, a minor cost compared with raw SFNT files.
Common Use Cases
WOFF is used to deliver custom fonts efficiently on websites.
CSS @font-face web fonts | FileFormer
WOFF is referenced in stylesheets to serve branded typefaces to site visitors.
Legacy browser fallback | FileFormer
Sites provide WOFF alongside WOFF2 so older browsers that lack WOFF2 still render custom fonts.
Font hosting services | FileFormer
Web font providers deliver WOFF to ensure wide compatibility across browsers.
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Try Font Converter FreeFrequently Asked Questions
What is WOFF used for?
WOFF is a web font format used with CSS @font-face to deliver compressed TrueType or OpenType fonts to web browsers, reducing download size.
Is WOFF the same as TTF?
No. WOFF is a compressed wrapper that contains the same SFNT font tables as a TTF or OTF, optimized for web delivery.
What is the difference between WOFF and WOFF2?
Both are web font wrappers, but WOFF uses zlib compression while WOFF2 uses Brotli, which compresses roughly 30% better, making WOFF2 the preferred modern format.
Do all browsers support WOFF?
Yes. WOFF has been supported by all major browsers for many years, making it a reliable baseline web font format.
When was WOFF standardized?
WOFF 1.0 was published as a W3C Recommendation on 13 December 2012.