A WOFF file is a web font file created in the WOFF (Web Open Font Format) format, an open format used for delivering webpage fonts on the fly. It is saved as a compressed container and supports TrueType (.TTF) and OpenType (.OTF) fonts and also supports font licensing information.

WOFF files allow web developers to use custom fonts rather than the standard web fonts. Many browsers support the WOFF format, but most of them do not support WOFF files until recent versions. WOFF files are referenced within CSS files using the @font-face rule. WOFF files were replaced with .WOFF2 files, which are saved in the WOFF 2.0 format that features improved compression. NOTE: FontForge allows you to create OTF and TTF font files from the WOFF file.