RoboFont uses UFO as its native font format.

RoboFont 3 adds support for UFO3. (RoboFont 1 supported UFO2 only.)

What is UFO?

UFO (Unified Font Object) is a cross-platform, cross-application, human-readable, future-proof format for storing font data.

The format was developed and is maintained by Erik van Blokland, Tal Leming, and Just van Rossum. The official UFO Specification is available at unifiedfontobject.org.

Because UFO is application neutral, several typeface design and font production applications use it natively; these are referred to as UFO Tools. Other applications can import from & export to UFO, using it only as a secondary format.

Advantages of UFO

Standards-based, future proof, easy to read and write.
Open and documented format
See unifiedobject.org for the official UFO Specification.
Each glyph in a file
Each glyph is stored separately – easy to access and track versions.
One can import/export UFO’s from FontLab, Glyphs, and FontForge.


RoboFont 3 upgrades from UFO2 to UFO3 as its native source format.

UFO3 introduces support for layers, as well as images, guidelines, data blocks, unique identifiers.

UFO2 in RoboFont 1 already had layers, but in a custom format, with some limitations (all glyph layers had the same width).

The new features of UFO3 offer improved interoperability between different editing tools, and enable new workflows based on layers.

UFO continues to be developed. The UFO Roadmap includes plans for UFO3 updates, and for UFO4.

UFO-based tools

Tool for kerning.
Tool to check fonts for interpolation compatibility.
Tool to build multi-dimensional interpolation spaces.
Tool to round the corners of glyphs (and more).
Tool to interpolate and transform glyphs.
Last edited on 08/03/2018