Fontdue automatically detects if your font is a variable font, and is generally treated the same as a traditional Family, with a few notable differences:

The variable font Family is marked in the admin with the VAR tag
When creating type testers for variable fonts, you may choose to expose Variable Axes to users. These are revealed in the OT Features panel
Type testers allow you to select named instances from the variable font. These are also automatically exposed to users in the “style selector” in place of a list of traditional styles
The end-user shopping experience annotates variable fonts with “Variable font” where relevant, and shows the range of named instances

Variable fonts styles

Variable fonts may have one or more files that make up the design space. These individual variable font files become Styles.

It is common to only have one Style for a variable font. In this case, we recommend only setting a price for the Family (Font collection). That way the name of the Style is not shown to the end user as it is not relevant.

You may opt to make each variable style purchasable as you would with traditional styles. In this case, the names of the variable Styles are shown during the shopping experience, so we recommend taking care to name these styles (for example, you may have “Upright” and “Italic”).

Named instances

It is important to include named instances in your variable fonts. We expect these to exist for the type tester to work correctly.

Variable fonts
Variable fonts styles
Named instances