LaserGRBL - LaserGRBL for Microsoft Windows is an all-in-one, open-source GCode streamer for DIY Laser Engraver developed using pure C# code.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
Universal Gcode Sender - A full featured gcode platform used for interfacing with advanced CNC controllers like GRBL and TinyG.
FreeCAD - An open-source parametric 3D modeler
OpenBuilds CAM & Control - OpenBuilds CAM & Control are two major applications that enable users to connect, manipulate, and convert drawings for use with DragKnife, CNC, Plasma, or Laser devices.
SketchUp - 3D for Everyone