OpenType-CFF2 variable font example

Adobe Variable Font Prototype

OpenType-CFF2 variable font made from UFO sources derived from Source Serif Pro, designed by Frank Grießhammer.

This font is intended to serve as a test and demonstration for environments and workflows that support the Compact Font Format flavor of the OpenType variable fonts.

The font is functional but it's not considered shippable — see Current limitations. We plan to update it as the tools improve.

Font characteristics

Adobe Variable Font Prototype contains two axes — weight and contrast — five design masters, and eight named instances — Extra Light, Light, Regular, Semibold, Bold, Black, Black Medium Contrast, and Black High Contrast.

The weight axis has an intermediate master (master_1), and the design space can be thought of as having the shape of a square triangle. This is achieved by using master_0 twice, and by having master_4 along the diagonal defined by master_0 and master_3. This arrangement effectively collapses half of the original rectangular-shaped design space, concealing interpolation imperfections that would be visible otherwise. See design space notes for more details.

The font also contains transitional designs for the glyphs $ (dollar) and ¢ (cent), in which the inner-counter part of the stroke is removed, when the weight axis reaches Bold or heavier.

The font supports the Adobe Latin 2 character set, GPOS kerning, and the GSUB features listed below.

pnum (proportional figures)
tnum (tabular figures [default])
onum (old-style a.k.a. text figures)
lnum (lining figures [default])
zero (slashed zero)
case (case-sensitive forms such as parentheses, hyphen)
liga (ligatures fi fl ft)

Downloading the font

Building the font from source


To build AdobeVFPrototype.otf from source, you need to have installed a custom build (2.5.65463 or later) of the Adobe Font Development Kit for OpenType which can be downloaded from

Build command

macOS and Linux:

$ sh


> cmd

Build process

The file calls two scripts, buildMasterOTFs and buildCFF2VF. The first script generates OpenType-CFF fonts from each of the UFO masters. And the second takes the set of OTF fonts built in the previous step, and combines them to produce an OpenType-CFF2 variable font. More details about the process are provided at

The build script finally runs TTX to make some changes to the name and GSUB tables. In the name table, the placeholder word Custom is changed to Contrast. And in the GSUB table, a feature variations table is added.

Current limitations

  • Adobe Variable Font Prototype cannot be displayed by macOS or Windows because their font rasterizers do not yet support the newer CFF2 table. (As of this moment, the only tool that can render OT-CFF2 fonts is FontView).
  • The font's glyphs will not be hinted because the AFDKO's autohint tool cannot yet produce hinting data that is compatible across a set of master fonts.
  • The font does not contain the required MVAR and STAT tables.
  • The font's CFF2 table lacks subroutinization.