SketchUp - 3D for Everyone
Universal Gcode Sender - A full featured gcode platform used for interfacing with advanced CNC controllers like GRBL and TinyG.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
CNCjs - A web-based interface for CNC milling controller running Grbl, Marlin, Smoothieware, or TinyG. - cncjs/cncjs
DraftSight - Discover Dassault Systèmes®' DRAFTSIGHT™ Professional CAD software that lets you create, edit, view and markup any kind of 2D drawing. Learn more here.
Candle - GRBL controller application with G-Code visualizer written in Qt