draw.io - Online diagramming application
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
DWGFREE - DWGFREE is an online platform that comes with a comprehensive collection of CAD blocks that can be downloaded without the need for registration.
Invision - Prototyping and collaboration for design teams
Cadbull - Cadbull is a website that comes with an advanced collection of CAD blocks and DWG design, facilitating architects and designers to get done with their projects efficiently.
Sketch - Professional digital design for Mac.