About xTools4

xTools4 is a fusion of hTools3 and variableValues extensions, updated to the new RoboFont 4 APIs: Merz, Subscriber, and EZUI.

• VariableValues
• hTools3
• xTools4

RoboFont 4, released in July 2021, introduces 3 new APIs:

• Merz, a completely new drawing back-end based on Apple’s Core Animation Layer framework. It is significantly faster than the previous API, and has an object-oriented approach.
• Subscriber, a new notification manager that is meant to work along with Merz. It makes subscribing to application events easier and more efficient.
• Ezui, a new toolkit that makes it easier to build user interfaces. It’s built on top of and is fully interoperable with vanilla.

RoboFont 3 tools still work fine in RoboFont 4, with small limitations such as blurry previews.

VariableValues

VariableValues is an open-source extension to assist in the production of variable fonts. It contains tools to view and edit data in multiple designspace sources, validate source glyphs against a default font, measure glyph parameters, work with sparse sources, etc.

While VariableValues still works in RoboFont 4, it was written using the old RoboFont 3 APIs, and does not take advantage of the new APIs introduced in RoboFont 4.

hTools3

hTools3 is a closed-source, commercial extension for RoboFont 3. It is a modular toolkit containing several small tools for basic font production tasks.

While hTools3 still works in RoboFont 4, it was written using the old RoboFont 3 APIs, and does not take advantage of the new APIs introduced in RoboFont 4.

xTools4

xTools4 is a collection of expert tools for typeface design and font production in RoboFont 4.

xTools4 is a fusion of hTools3 and VariableValues extensions, updated to the new RoboFont 4 APIs: Merz, Subscriber, and EZUI.

xTools4 is available as an open-source extension from the xTools4 repository on GitHub.