The Addon Academy is your one-stop shop for documentation about creating and maintaining a FreeCAD Addon of any variety. The Guides section below is a top-down list of steps you’ll want to go through to author an Addon, while the Topics section covers several specific topics, and of course the Demos section contains sample code (all licensed CC0, so you are welcome to take whatever you need, no attribution is required, etc.).

Guides

Step-by-step how-tos.

• Creating an addon: starting from the GitHub template repository or the cookiecutter generator. Pros and cons of each.

• Writing addon code: the details of creating an Addon: workbenches, commands, Qt UI, preferences, custom document objects, icons, translations, and logging.

• Developing locally: installing your addon into FreeCAD’s Mod/ directory, debugging, and writing tests.

• Publishing your addon: ZIP archives, repository URLs, and the official Addon Index.

• Polishing for users: making things look nice: writing an overview page, manifest metadata, and selecting screenshots.

• Maintaining an addon: cross-version compatibility, data migrations, and handing the project off to a new maintainer.

Topics

Reference material on how addons fit into FreeCAD.

• Types of addon: workbench, macro, preference pack, bundle, and other.

• Structure of an Addon: modern namespaced layout, legacy layout, and the package.xml manifest.

• Dependencies: the Addon Manager’s allow-list, and when to vendor a library instead.

• Licensing: choosing licenses for code and assets, and SPDX identifiers.

• Addon Index: the official registry, its quality requirements, and addons that have been removed from it.

• Glossary: terminology used throughout the Academy and the wider FreeCAD ecosystem.

Demos

Worked examples with runnable source code.

• Add a command to an existing toolbar: the smallest unit of addon functionality, building on what FreeCAD already ships.

• Minimal Workbench: a complete but stripped-down workbench, suitable as a starting point for a new one.

• Parametric Feature: a custom document object with an execute() method and its own ViewProvider.

• Preferences Page: an addon-supplied page under Edit → Preferences driven by a Qt Designer .ui file.

• Macro: distributing a single-file .FCMacro as a standalone addon.