LibreCAD Easily create and edit various types of CAD files for free -- 2D PPM, XBM and XPM formats included.
Autodesk Fusion 360 Powerful collaboration CAD editing and viewing software for sharing and modifying your 3D models with CAD and CAM projects.
FreeCAD A free CAD modelling editor which can assist in creating drawings and objects in both the 2D and 3D space with drawing tools.