Reference

UFO (font source)

UFO (Unified Font Object) is an open, editable source format for fonts. Rather than a finished file, a .ufo is a folder of XML files describing every glyph and setting, used by type designers before exporting to TTF or OTF.

Files & formatsGeneral

UFO (font source)

Also known as: .ufo file, Unified Font Object, UFO source

Open, editable source format for fonts
A folder of XML files, not a single binary
Exported to TTF or OTF for actual use

UFO as a source format

A UFO is the editable master, not the shipped font. It stores each glyph and the font’s metadata as human-readable XML, so the work can be version-controlled and shared across tools like Glyphs, RoboFont, and FontForge.

Although it ends in .ufo, it is actually a folder (package) containing many files, not a single binary.

From UFO to a usable font

Browsers and operating systems cannot use a UFO directly. Designers export it to TTF or OTF (and then WOFF2 for the web) to produce the installable, distributable font.

Related terms

Keep reading the reference.

Files & formatsSFD (FontForge)SFD (Spline Font Database) is the native source format of FontForge, the open-source font editor. It stores a font project’s glyph outlines and settings as editable text, separate from the finished TTF or OTF you export.General Files & formatsOTF (OpenType font)OTF (OpenType) is a modern, cross-platform font format from Adobe and Microsoft. It stores scalable outlines like TrueType but adds advanced typography — ligatures, alternates, and small caps — making it the common choice for professional type.General Files & formatsTTF (TrueType font)TTF (TrueType) is a widely supported font file format developed by Apple and Microsoft. It stores letter shapes as scalable outlines so text stays sharp at any size, and a single TTF holds one font style such as Regular or Bold.General