Best open-source alternatives to AutoCAD

FreeCAD is an open-source parametric 3D CAD application aimed at designing real-life objects of many sizes. It is intended for a broad audience, including product designers, mechanical engineers, architects, hobbyists, students, teachers, and programmers who need a flexible modeling tool. The project supports a workflow that starts with constrained 2D sketches and extends them into 3D models, with the ability to revise designs by changing parameters in the model history. It runs on Windows, macOS, and Linux, and its functionality is built around OpenCASCADE, Coin3D, Python, and Qt. The README also points users to precompiled downloads, Linux software centers, and source compilation instructions.

OpenSCAD is a free, cross-platform CAD application for creating solid 3D objects from scripts rather than through direct interactive modeling. It is aimed at users who want precise control over geometry, especially for machine parts, parametric designs, and other technical models where editable, code-driven workflows are useful. The project supports constructive solid geometry and extrusion-based workflows, and it can read or generate common formats such as DXF, STL, and OFF. The README also documents how to build the software from source on multiple platforms, including macOS, Linux/BSD, Windows cross-compilation, Nix, and WebAssembly, which suggests it is intended both for end users downloading binaries and for contributors or packagers working from source.

LibreCAD is a free, open-source 2D CAD application aimed at users who need a lightweight tool for drafting and editing technical drawings. It is built on Qt and is designed to run on most operating systems, with translated user interfaces available in many languages. The project focuses on core CAD workflows and also includes a command-line DXF converter that can produce PDF, PNG, or SVG output from DXF files. Its README points users to release downloads, user documentation, forum support, and source code build instructions, indicating that it serves both end users and contributors who want to build from source or work on the codebase.

nurb is a CAD-oriented assistant for 3D printing that helps users describe parts in plain language and have them modeled, validated, and exported for printing. It is aimed at people who want to design functional printed parts without doing all the geometry work manually, while still keeping control through sliders, checks, and a live viewer. The project centers on a local Python-based workflow built on build123d and the OCCT kernel, with parts represented as functions whose parameters drive the UI and CLI. It includes printability rules, stress analysis, measurement capture, scan comparison, and print-ready export formats such as 3MF, STL, STEP, and GLB. The README emphasizes that it works offline, requires no account, and can be driven either from the desktop app or through terminal commands.