BearCAD

Local-first, parametric CAD. Built by robots to see what AI can do.

Solid geometry by OpenCASCADE (OCCT), the industry-grade BREP kernel; sketch constraints solved by SolveSpace's solver (libslvs) — on desktop and in the browser alike.

Docs

Download

Or skip the download: run BearCAD in your browser (full geometry engine and constraint solver; documents save as downloads).

Platform	Download
macOS (Apple Silicon)	bearcad.dmg
Windows (x86_64)	bearcad.exe
Linux (x86_64)	bearcad-linux-x86_64.tar.gz

Run

cargo run

• Pick a face with the Sketch tool (or start on the default XY construction plane), then draw with Rectangle, Line, or Circle.
• Type dimensions while drawing; Tab cycles fields; Enter commits.
• Right-drag to orbit; Shift+right-drag to pan; mouse wheel to zoom.
• Escape cancels an in-progress draw; press again to exit sketch mode or return to Select.
• Save / Save As… writes a .bearcad SQLite file; Open… loads one back.
• Clear resets the document; Undo last reverts the most recent action as a whole (e.g. an entire rectangle — its lines and constraints — in one step).

cargo run -- --help    # usage and exit
cargo test

Building with the OCCT kernel

BearCAD's real BREP geometry kernel is OpenCASCADE (OCCT), behind the occt Cargo feature, which is on by default — solid booleans/cut, true BREP fillets/chamfers, and curved-surface STEP all come from the kernel. So the default cargo build / cargo run needs a built OCCT; set that up once:

# 1. Install OCCT (downloads a prebuilt when one matches; Windows: scripts/build-occt.ps1):
scripts/build-occt.sh

# 2. Build/run BearCAD (the default build links the kernel):
cargo run

scripts/build-occt.sh first tries the prebuilt static libraries published by the occt-prebuilt workflow — keyed to the pinned OCCT submodule commit and the build script itself, checksum-verified — so a fresh clone is building BearCAD in minutes with no OCCT compile. When no prebuilt matches your platform (or with BEARCAD_OCCT_FROM_SOURCE=1), it compiles from source instead: fetch the submodule (git submodule update --init --depth 1 third_party/OCCT) and have cmake + a C++17 toolchain on PATH. Either way the result lands in third_party/OCCT/occt-install — the modeling toolkits plus DataExchange (for STEP read/write), no visualization/application-framework/Draw — which build.rs statically links against.

Recompiling against a different OCCT version

BearCAD links OCCT statically. The LGPL 2.1 permits this on the condition that you can relink the app against a different (e.g. modified or newer) OCCT. To do so, point the OCCT_DIR environment variable at any OCCT install prefix — one containing include/opencascade/*.hxx and lib/libTK*.a — and rebuild:

OCCT_DIR=/path/to/your/occt-install cargo build

When OCCT_DIR is set it takes precedence over the bundled submodule build, so you can swap in your own OCCT (from Homebrew, a distro package, or a custom build) without touching BearCAD's source. See THIRD_PARTY_LICENSES.md for the full licensing story.

Kernel in CI and releases

CI (.github/workflows/ci.yml) has dedicated occt (Linux) and windows-occt (Windows/MSVC) jobs that build OCCT once (cached on the pinned submodule + build script, so it's restored rather than rebuilt on later runs) and run the full test suite — plus the launch smoke, example scripts, and interaction tests — against the kernel build, so kernel regressions are caught on every push/PR.

All release binaries — macOS, Linux, and Windows — ship with the kernel (the default build), so real BREP fillets/chamfers, solid booleans/cut, and curved-surface STEP work the same on every platform.

Scripting

Scripts are Lua files (.lua) that call the global bearcad API — the same actions and synthetic input as the GUI, useful for automation and regression tests. Full docs, including the complete API reference, are at iffy.github.io/BearCAD/docs/scripting.

Run a script:

cargo run -- --script examples/rectangle.lua --exit

-- examples/rectangle.lua
bearcad.new()
bearcad.rect{ width = 80, height = 50, name = "Main box" }

Interactive REPL — drive the live app from your terminal, entry by entry (the GUI stays fully usable while it runs):

cargo run -- --repl

bearcad> x = 15
bearcad> bearcad.rect{ width = x * 2, height = x }
bearcad> 1 + 2
3
bearcad> bearcad.save("drawing.bearcad")