RazorCAD

Parametric 3D CAD for Windows. Free and open source.

Sketch with constraints, build parts feature by feature, put them together in assemblies and make drawings. RazorCAD runs offline on the OpenCascade kernel, and it’s yours to use, share and change.

Download for Windows View the source on GitHub

Version 0.11.0-beta, 33 MB. Windows 10 and 11. GPL-3.0.

RazorCAD with a part of six bodies open: a copper cylinder, a stainless steel square boss with a threaded hole, a second body with a square pocket, a reference plane and an axis. The feature tree lists every step on the left.
What you’re looking at
ItemDescription
1The command ribbon, with tabs for features, sketches, surfaces, sheet metal, weldments and evaluation.
2Solid and surface bodies. Each body can have its own name, material and properties.
3The feature tree: the part’s history. Change any step and everything after it rebuilds.
4Reference planes, axes and points that follow the model when it changes.
5Standard views, display styles, section view and selection filters.

Sketches that hold their shape

Draw lines, arcs, circles, slots and splines, then pin them down with relations and dimensions. A constraint solver keeps everything in place. Geometry turns from blue to black once it’s fully defined, and the Property panel tells you how many degrees of freedom are left.

  • Smart Dimension, with equations and global variables in any value
  • Trim, offset, mirror, pattern and convert model edges into the sketch
  • Import DXF files straight into a sketch
  • Hold the middle mouse button for a tool wheel
A fully defined sketch of a mounting plate, 120 by 80, with horizontal, vertical and midpoint relations shown as small green glyphs.
Sketch1 on the Top Plane, fully defined

Parts built one feature at a time

Every boss, cut, fillet and pattern is a step in the feature tree. While you set one up, RazorCAD rolls the part back and previews it: yellow for material added, red for material removed.

  • Extrude, revolve, sweep and loft, as bosses or cuts
  • Fillet, chamfer, shell, draft, rib, Hole Wizard and threads
  • Linear, circular, curve and sketch driven patterns, and mirror
  • Several bodies per part, with Combine, Split and Move/Copy
  • Surfaces, sheet metal with flat patterns, and weldments with a cut list
  • Mass properties from each body’s material
The sample mounting plate in an isometric view: a rectangular plate with four holes, two slots and a round boss, with its feature tree.
The sample part, in 6061 aluminium

Drawings for the workshop

Make a drawing from a part or an assembly and RazorCAD lays out the three standard views for you, in first or third angle projection. Add the views and notes you need, then export a PDF or DXF.

  • Projected, section, detail, auxiliary, broken and cropped views
  • Dimensions, hole callouts, cut lists and sheet metal flat patterns
  • Your own templates, title blocks, logos and fonts
  • Export any flat face as a DXF for laser or waterjet cutting
An A3 drawing of the mounting plate with front, side and top views, a zoned border and a filled-in title block.
Standard three views on an A3 sheet

Assemblies and the files you already have

Put parts together with mates, nest sub-assemblies, explode them and list them in an indented bill of materials. Open a STEP assembly and it keeps its structure and colours. Big assemblies reopen in seconds.

File formats
FormatOpensSaves
STEPParts and assemblies, with coloursExact solids, one per body
STLMeshes up to 200,000 trianglesBinary mesh
DXFInto a sketchFaces, flat patterns and drawings
PDFDrawings, with fonts embedded
RazorCAD.rcad parts, .rasm assemblies and .rdrw drawings, saved as readable JSON

Why RazorCAD exists

I’m a mechanical engineer, not a professional programmer. I couldn’t find an open-source CAD program that suited the way I work, so I started building one, with a lot of help from open-source libraries and Claude. My aim is a capable alternative to expensive CAD, subscriptions and paywalls, for makers and professionals alike. Built-in CAM and FEA are on the list for later.

Found a bug or missing a feature? Open an issue on GitHub.

Common questions

Is RazorCAD really free?

Yes. There’s no subscription, licence key or account, and you can use it for commercial work. RazorCAD is open source under the GPL-3.0, and the parts, assemblies and drawings you make with it are yours.

Does it need an internet connection?

No. RazorCAD runs entirely on your PC and works offline. The setup program only goes online to fetch the Microsoft WebView2 runtime or .NET Framework if Windows is missing them.

Does it run on Mac or Linux?

Not at the moment. RazorCAD is a Windows program and runs on Windows 10 and 11.

Can I open files from other CAD programs?

Yes, through STEP, STL and DXF. STEP assemblies open with their structure and colours, STL meshes become solid bodies, and DXF files import into a sketch. RazorCAD also saves STEP, STL, DXF and PDF.

What does it use for geometry?

The OpenCascade B-rep kernel, the same engine behind FreeCAD, so STEP files come in and go out as exact solids rather than meshes.

Is it ready for production work?

It’s a beta, so expect some bugs. Check exported DXF files before you cut anything, and report problems on GitHub.

Install RazorCAD

  1. Download the setup program from the latest GitHub release.
  2. Run it. Install just for you, without administrator rights, or for everyone on the PC. Setup adds the Microsoft WebView2 runtime and .NET Framework 4.8 if Windows doesn’t have them yet.
  3. Open RazorCAD from the Start menu and try the sample part, or start a new one.

Running setup again updates RazorCAD. Your parts, assemblies and drawings are never touched.