Files with the .WOFF extension contain compressed fonts created in an open network format. They support TTF and OTF font types and potential license information. It was created for the loading of non-standard fonts online, for use by websites. Currently, most web browsers support new versions of these files, which follow the WOFF2 standard, which supports better data compression.

WOFF files are referred to in FontFace rules in CSS style sheets. The FontForge software allows its users to extract TFF and OTF fonts from WOFF files.