brepjs
Exact boundary representation CAD in TypeScript built so AI agents can write parts and check them against OpenCascade, with a Claude Code plugin and STEP and STL output.
What it does and how it connects
brepjs is exact boundary representation CAD in TypeScript, built so AI agents can write parts and check them. Parts are plain TypeScript files, shapes are exact mathematical boundaries rather than triangle meshes, so booleans are precise, measurements are real, and models export to STEP.
The brepjs-cad package helps an agent author CAD and prove it correct before handoff: the agent writes a part file, runs it on a real kernel, and reads a deterministic report. It ships as a Claude Code skill and a verification CLI that checks validity, measured dimensions, multi-view snapshots, and STEP export, and it exits non-zero unless the report is ok. MCP clients can use the brep-mcp server instead.
The README records a measurement: an agent rebuilt the 46 parts in the example gallery from their descriptions, and all 46 passed verification. brepjs itself is Apache-2.0; the kernel it registers carries its own license, and the occt-wasm default kernel is LGPL-2.1-only while a newer brepkit-wasm kernel is AGPL-3.0-only or commercial.
Alternatives
Compare side by side- build123d
A Python code-first CAD library, while brepjs is exact B-Rep CAD in TypeScript with a verify CLI for agents.
- text-to-cad
Generates CAD from text prompts through coding agents, while brepjs is a TypeScript library for writing and checking exact parts.
- chili3d
A browser CAD application, while brepjs is a programmatic TypeScript library with no visual editor or viewport.
- SolidCraft
A desktop CAD program with an MCP server, while brepjs is a TypeScript library that agents use to write and verify parts.
- VibeCAD (rawwerks)
A library of Claude Code skills for CAD tools, while brepjs is the CAD library itself, with its own authoring skill and verify CLI.
Recurring errors it addresses
Error Index entries this tool is built to reduce or work around.
Sources
Not verified
- Pricing (none stated on the repo)
- Real user voices (the repo has no open issues)
Last verified November 6, 2026. Listings are informational. The evidence score measures public, verifiable evidence and is not an endorsement or a compatibility claim.