pythonocc-core is a Python binding layer for the OpenCASCADE Technology (OCCT) 3D CAD kernel, built around SWIG-generated wrappers. The repository exposes nearly the entire OCCT C++ API to Python through OCC.Core.* modules, covering geometric modeling (BRep, Geom, TopoDS), boolean and fillet operations, STEP/IGES/STL/glTF data exchange, meshing/tessellation, OCAF document persistence, and interactive 3D visualization. On top of the generated bindings, hand-written Python modules in src/Display and src/Extend provide a user-friendly entry point: multi-backend GUI viewers (Qt, wx, tkinter), offscreen rendering, WebGL/Jupyter rendering, topology iterators, shape factories, and high-level file I/O helpers. The repo also contains custom C++ components including a shape tessellator and an OpenGL display wrapper that SWIG alone cannot express. In production, this is a library rather than a standalone application: users import OCC.Core and the high-level helpers to script CAD workflows, convert between file formats, analyze geometry, or build custom visualization tools. The dominant character is clearly an application/library for computational geometry and CAD interoperability, though it carries a data-exchange flavor because STEP/IGES/mesh I/O is a first-class capability. The project is actively maintained, with a recent 8.0.1.2 release targeting OCCT 8.0.1, CI for Windows/macOS/Linux, and a substantial test suite covering geometry, topology, display backends, data exchange, and tessellation. Technical drift is moderate: most of the codebase is generated SWIG surface with occasional OCCT 7.9.0 documentation links, incomplete type stubs, and a legacy WebGL template using unpinned CDN assets, but the core bindings track the current OCCT release and engineering workarounds are actively patched.