FreeCAD is a mature, open-source parametric 3D CAD application with a modular workbench architecture. The codebase reveals a well-structured monolithic desktop application written in C++ with extensive Python bindings. The core uses OpenCASCADE as its geometry kernel, Coin3D (Open Inventor) for 3D scene representation, and Qt for the GUI. The architecture separates the application logic (App) from the GUI (Gui), with a Base layer providing fundamental utilities (math, units, persistence, Python integration). Workbenches (PartDesign, Sketcher, Draft, Arch, FEM, CAM, Mesh, etc.) are implemented as loadable modules that extend the document-object model. The parametric engine supports expression-driven constraints, a full dependency graph with topological naming, and a sketcher solver for 2D constraints. The FEM workbench includes a solver framework supporting CalculiX, Elmer, and Z88. The CAM workbench provides CNC toolpath generation with post-processing. The codebase demonstrates strong engineering practices: comprehensive unit tests, CI/CD pipelines, modern CMake, C++17, and clean separation of concerns. With 31k+ stars and active development (last commit June 2026), it's a production-grade CAD system used by hobbyists and professionals alike.
This is a software library for parsing and processing IFC (Industry Foundation Classes) BIM files, primarily designed for web environments. It consists of a C++ core that reads IFC STEP files, resolves geometry (including extrusions, sweeps, Boolean CSG operations, and advanced curves like B-splines and clothoids), and generates triangulated meshes. The C++ code is compiled to WebAssembly via Emscripten, and a TypeScript API (IfcAPI) exposes all functionality to JavaScript applications in both browser and Node.js. The library supports multiple IFC schema versions (IFC2X3, IFC4, IFC4X3) and includes a schema generator that produces C++ and TypeScript type definitions from EXPRESS schema files. The architecture is a classic native-to-web bridge: the C++ library handles all heavy geometry and parsing, while the TypeScript layer provides a clean interface for loading models, streaming meshes, reading/writing properties, and creating new geometry. Key entry points include the IfcAPI class (open/close models, load geometry, save models), the C++ IfcGeometryProcessor and IfcGeometryLoader for mesh generation, and the IfcLoader for token-based IFC parsing. External dependencies include GLM (math), spdlog (logging), mapbox/earcut (triangulation), and CDT (constrained Delaunay triangulation). A comprehensive test suite using real IFC files and regression hash checks ensures geometry stability across versions. The library is production-ready but shows some technical drift: pinned dependency commits, large monolithic source files, and generated schema headers that must be manually regenerated. It remains actively maintained with CI/CD pipelines, issue triage, and regular releases (v0.0.78).