brepjsCAD modeling for JavaScript.

Exact B-Rep geometry, type-safe at compile time, browser-native via WASM.

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Exact B-Rep, not triangles

Shapes are mathematical boundaries — faces, edges, vertices — so booleans are precise, measurements are real, and you can export to STEP.

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If it compiles, it's valid

Branded types and validity brands (ClosedWire, OrientedFace, ValidSolid) prove topological invariants at compile time. Not just type-safe — geometry-safe.

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Two kernels, one API

OpenCascade WASM ships today. brepkit (Rust-based) is a faster drop-in replacement under active development. Switching is one line.

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Built for the JS ecosystem

ESM, top-level await init, Three.js mesh adapter, web-worker friendly. Plays well with Vite, Next.js, and React Three Fiber.

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Sketcher + functional API

Build 2D profiles fluently, extrude into solids, then chain booleans, fillets, shells. Or stay fully functional — both surfaces are first-class.

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Everything imports/exports

STEP, STL, BREP, IGES, glTF, DXF, 3MF, OBJ, SVG. Round-trip with SolidWorks, Fusion, FreeCAD, OpenSCAD.

Build a part in five lines

typescript

import { box, cut, cylinder, fillet, edgeFinder, exportSTEP, unwrap } from 'brepjs/quick';

const drilled = unwrap(cut(box(30, 20, 10), cylinder(5, 15, { at: [15, 10, -2] })));
const part = unwrap(fillet(drilled, edgeFinder().inDirection('Z').findAll(drilled), 1.5));
const step = unwrap(exportSTEP(part));

Drill a hole, fillet the vertical edges, export to STEP. The full code-CAD loop in five lines. Want to see it run? Hover the snippet above and click Open in Playground.

Where to go next

New here? Start with Why brepjs and Your First Solid.
Coming from another library? See Migration.
Need a specific operation? Jump to Common Tasks.
Curious about the type system? Read Types That Prove Geometry Is Valid.