Electrical
KiCAD
Open Source
With ECAD software, there’s really only one serious option: KiCAD. KiCAD is a powerful, professional PCB design package. It has a vast plugin system, and being open source means it has a ton of automation potential. Lots of the other tools on this page rely on the fact that KiCAD is the EDA of choice.
WireViz
Open Source
WireViz is a fantastic way to document your cables and wire harnesses. Using a simple YAML file, you can define complex cable harness assemblies in a git-trackable filetype, and easily export beautiful graphical output for an engineering drawing or assembly technician.
Mechanical
FreeCAD
Open SourceGithub CI
FreeCAD is the most mature, stable, and fully-featured open source mechanical cad package. It has the traditional user experience of other desktop CAD software instead of being software-defined like most other open MCAD suites.
FreeCAD can be easy to learn, but feature trees are notoriously fragile due to the Topological Naming Problem. The most consistent way to deal with this issue is to use a Direct Modeling methodology, as opposed to a Parametric one. The main difference between the two is that Direct Modeling does not go back in the feature tree, only ever adding on new cuts and extrudes. It is also possible to have parametric designs in FreeCAD with careful use of datum planes.
This being said, this issue is actively being addressed by the FreeCAD community, and the open-core company Ondsel based on the FreeCAD project.
OpenSCAD
Open Source
CADQuery
Open Source
Blender
Open Source
can only run CI in the way that it can render an existing .blend file, doesnt seem to be able to edit that .blend file at all