Morpholio Trace - Morpholio Trace is widely called to be the dream software of the designers and architect.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
DWG FastView - DWG FastView for Windows is a lightweight dwg/dxf drawing viewer and editor produced by Gstarsoft, no need of dwg format conversion, vector graph magnified without distortion and full compatible with AutoCAD DWG/DXF.
Invision - Prototyping and collaboration for design teams
Drawing Desk - Drawing Desk Draw Paint Color, Doodle and Sketch Pad created and published 4Axis Technologies for Android and iOS devices.
Sketch - Professional digital design for Mac.