File extension

.woff2

Web Open Font Format (WOFF) 2.0

.woff2 files are Web Open Font Format 2.0 fonts: Brotli-compressed wrappers around TrueType or OpenType fonts, now the usual format for web font delivery.

Known meanings

Formats and reference material for .woff2

Web Open Font Format (WOFF) 2.0

Brotli-compressed sfnt font wrapper with font-specific table transforms, a W3C Recommendation

  • fonts internet
  • W3C
Open link

Details

Format notes

WOFF2

WOFF2 is the second version of the Web Open Font Format, published by the W3C. Like WOFF 1.0 it repackages an sfnt-based font (TrueType or OpenType) for web delivery, but it achieves noticeably smaller files by using Brotli compression and by preprocessing some font tables before compression.

Structure

A WOFF2 file starts with the signature wOF2. The header records the font flavor and sizes and is followed by a compact table directory. All table data is compressed together as one Brotli stream rather than table by table. Certain tables, notably the glyph data (glyf and loca), can be stored in a transformed form that is more compressible and is reversed on decoding. WOFF2 also supports font collections, and like WOFF it can carry an optional metadata block and private data.

Adoption

All current major browsers support WOFF2 through CSS @font-face, and it is usually the only web font format that a modern site needs to provide. The media type is font/woff2 (RFC 8081). Many font tools and the open-source woff2 reference implementation can create and read it.

Preservation And Security Notes

WOFF2 is a delivery format. Keep the original OpenType or TrueType source and its license for archiving, because the WOFF2 file is derived from it and conversion may drop or alter tables. As with all font parsers, decoders should check declared sizes, table offsets, and transform data when handling untrusted files.

Further Reading

  • WOFF File Format 2.0 (W3C): https://www.w3.org/TR/WOFF2/
  • RFC 8081, font media types: https://www.rfc-editor.org/rfc/rfc8081