ProstoCAD is free to use. It is built on the ProstoCAD for FreeCAD workbench (formerly InCad), which is open source under the GNU LGPL 2.1 or later, the same license as FreeCAD. Its own additions (STL tools, AI link) are not open source.
ProstoCAD bundles the open-source components below, unmodified as built by conda-forge, each under its own license. It is an independent project, not made or endorsed by the FreeCAD project.
Source code. Each component's upstream source and its conda-forge package (which carries the recipe and patches) are linked below. The source of every GPL-licensed component is mirrored with the release. For at least three years from each release we also provide, on request, the complete corresponding source of any GPL or LGPL component for no more than the cost of distribution: ask here.
All license texts in one file: THIRD-PARTY-NOTICES.txt · ProstoCAD 0.12.0, macOS and Windows · 87 components