ProtoJoint Open the editor

Documentation

ProtoJoint documentation

Updated

ProtoJoint is parametric CAD that runs in your browser. If you are new, start with Getting started: it takes you from an empty design to an exported part in five minutes. Each other page answers one question, with the answer first.

The pages

  • Getting started: Open ProtoJoint in a browser, sketch a rectangle, extrude it, round its edges, and save or export the result. What you need, where files are kept, and how to move the view.
  • Sketching and constraints: Draw 2D sketches on planes and faces with snaps that become constraints and typed values that become dimensions, see what is still free, and edit with trim, offset, fillet, mirror and patterns.
  • Features: Make solids with extrude, revolve, sweep and loft, change them with holes, fillets, chamfers, shells and drafts, copy them with patterns and mirrors, and edit any step on the timeline.
  • Parameters: Name dimensions, write expressions such as Width + 2*Wall in any number field, keep user parameters in one dialog, and change a whole design by changing one value.
  • Assemblies and joints: Build assemblies from components, connect them with rigid, revolute, slider, cylindrical, pin-slot, planar and ball joints, drive and limit the joints, and check interference and mass.
  • Import: Bring STEP, .sldprt and .sldasm, and Parasolid files in as solids; DXF and SVG drawings into sketches; STL, OBJ and 3MF meshes as reference bodies; and pictures to trace.
  • Export: Save a design as STEP for other CAD programs, as 3MF, STL or OBJ for 3D printing at the refinement you choose, a sketch as DXF for laser and CNC software, and as ProtoJoint’s own file.
  • AI: Model by asking: Eleph, the built-in AI design assistant, and MCP connections that let Claude Desktop, claude.ai, Claude Code, Cursor and other AI apps work on the design open in your browser tab.
  • Robot export: Turn an assembly into a robot description: links from components, joints from assembly joints, inertia from the exact solids, checked before export, as URDF, MJCF, SDF or a ROS 2 package.
  • Laser and CNC: Design flat parts with constraints and a material thickness parameter, generate finger-jointed boxes and living hinges, and export SVG or DXF with kerf compensation and colour layers for LightBurn and xTool.

How the pages write things

  • Keys look like E. On a Mac, Ctrl-click to add to a selection is Cmd-click.
  • Names of buttons and commands are written as they appear in the English interface, in bold: New sketch, Finish sketch. The interface also comes in Chinese: it follows your browser’s language, and the language menu at the right of the header switches it.
  • Most commands are also in the toolbox: press S and type a few letters of the name.

Something missing or wrong?

If a page does not answer your question, or the editor does something a page does not describe, send us a note. The documentation is updated with the editor; each page shows when it last changed.