SimplMaker
A small, native, parametric CAD tool for macOS, made for people who 3D print. You sketch, extrude, fillet and chamfer; every
size is an expression that can use named parameters, so changing a number rebuilds the whole part. Free and open source, with no
account, no subscription and no cloud: your parts are plain files on your Mac.
Download it · Documentation · Report a bug
SimplMaker runs on macOS 15 or later on Apple silicon. The download is signed and notarized, and updates itself.
Build it yourself
You need a Mac with Apple silicon, Xcode 26 or later (Swift 6.2), and CMake and Ninja to build the geometry kernel once:
brew install cmake ninja
git clone https://github.com/atlemo/SimplMaker.git && cd SimplMaker
scripts/build-occt.sh # once: builds OpenCASCADE 8.0.1 into ThirdParty/occt (30 to 60 minutes)
scripts/bundle-app.sh --debug --open # builds dist/SimplMaker.app and launches it
Launch the bundle rather than using swift run: the bundle declares the .simplmaker document type, which Open Recent, autosave
and versions depend on. You can also open SimplMaker.xcodeproj in Xcode, choose the SimplMakerApp scheme and press ⌘R.
Sources/SimplMaker is a synchronized folder, so new Swift files there join the app without being added to the project.
swift test # unit and integration tests
scripts/test-kernel.sh # the C-level kernel test (also runs on Linux)
scripts/bundle-app.sh # a release build, ad-hoc signed, in dist/
A build you make yourself has no update feed and sends no usage statistics. Only the builds the project publishes
(scripts/bundle-app.sh --official, run by scripts/release.sh) check for updates and, unless the user turns it off in
Settings → General, send anonymous usage statistics to TelemetryDeck. What is sent is in
Sources/SimplMaker/Telemetry.swift; the privacy page on simplmaker.com says how it is used. If you add a signal, keep that page in step.
The version comes from VERSION, and the build number from the commit count.
Architecture
| Layer | What | Where |
|---|
| App | SwiftUI panels, AppKit + Metal viewport with GPU ID-buffer picking | Sources/SimplMaker |
| Core | Expressions with units, parameters, sketch model, constraint solver, document model. Pure Swift with no dependencies. | Sources/CADCore |
| Kernel (Swift) | Wrappers and the timeline regenerator | Sources/CADKernel |
| Kernel (C API) | Plain C API over OpenCASCADE, with persistent face/edge naming | Sources/CKernel |
| OpenCASCADE 8 | Minimal build, linked as the replaceable libSimplOCCT.dylib | ThirdParty/occt (built by scripts/build-occt.sh) |
Faces and edges have persistent names built from stable IDs and the kernel's history. For example, an extrusion's top face is plate.end, and the edge between two of its sides is plate.side.L0|plate.side.L1. Features refer to geometry by these names, so a fillet stays on the right edge when you change the dimensions upstream.
See PLAN.md for the design notes and roadmap, and docs/FEATURE-NOTES.md for how each feature behaves.
Contributing
Bug reports, ideas and pull requests are welcome: see CONTRIBUTING.md.
License
SimplMaker is free software: you can redistribute it and change it under the terms of the
GNU General Public License, version 3 or later. Copyright © 2026 Atle Mo.
The name SimplMaker and the app icon are not covered by the GPL: see TRADEMARK.md before you publish a modified version.
SimplMaker builds on other free software, whose licenses are shown under SimplMaker → About SimplMaker (the texts are in
Sources/SimplMaker/LicenseTexts.swift):
- OpenCASCADE Technology, the geometry kernel: LGPL-2.1 with the OCCT exception. It is built unmodified
and linked as a separate library,
libSimplOCCT.dylib, so you can replace it with your own build; see
the documentation. The parts of OCCT that SimplMaker uses include DelaBella (MIT)
and flex's FlexLexer.h (BSD).
- Sparkle for updates (MIT) and the TelemetryDeck SDK (MIT).
- The toolbar icons are from Lucide (ISC; parts from Feather, MIT).
