Chili3D is a web-based 3D CAD application for online model design and editing. It features a modular TypeScript architecture with core packages for foundations, application logic, UI, Three.js rendering, and WebAssembly bindings to OpenCASCADE for CAD operations. The system uses a command pattern with decorators for UI actions, a transaction system for undo/redo, and a plugin architecture for extensibility. Key capabilities include primitive shape creation, Boolean operations, extrusion/revolve/sweep/loft, snapping, measurement tools, document management with IndexedDB persistence, and import/export of STEP, IGES, STL, and BREP formats. The UI implements an Office-style ribbon interface with property panels and hierarchical scene tree. The application is actively maintained with recent commits and demonstrates strong engineering practices in its reactive primitives, plugin system, and serialization framework.