Extrudo

Extrudo is a free, open-source parametric CAD tool designed for 3D printing. It runs entirely in the browser with no installation or account required, and works offline after initial load. Users sketch 2D profiles, extrude them into solids, apply fillets and other features, then modify parameters to update the entire design automatically.

Built for makers designing brackets, boxes, clips, enclosures and replacement parts. Features constrained sketching, exact geometry (real circles and fillets rather than triangle meshes), parameter-driven design, import/export of standard file formats, and built-in 3D printing checks. Desktop apps available for Linux, macOS and Windows. Designs are stored locally on your machine.