parcad

ParCAD is parametric CAD written as code, for people and for agents. A script builds a small JSON graph and an exact OpenCASCADE kernel reads it, producing real faces and edges with STEP export and a refusal rather than an approximation when it cannot do something faithfully. It is built by Maging Studio and is at version 0.0.14, experimental.

Selectors are descriptive and checked: a selector that silently matches the wrong number of edges becomes a build error instead of a wrong part. Parts are measured after the build, with volume, wall thickness and whether bores meet, and an agent gets the same numbers over MCP. The app serves its UI and an MCP endpoint on 127.0.0.1:4242, and a browser tab can also act as the server.

Install with Homebrew on macOS or Linux, or download the desktop app for macOS, Linux or Windows. It targets small mechanical parts such as brackets, flanges, manifolds and heat sinks, and ships 31 example parts. The README warns that the DSL still moves and that no part has had the years of abuse that make a kernel trustworthy, so a part should be measured before it is machined.