InVision was an early pioneer in design prototyping and collaboration, once valued at $2B, before declining after Figma's rise.
Vectr is a completely free cross-platform vector graphics design tool offering a web editor and desktop apps with real-time collaboration and automatic sync, ideal for vector design beginners and light graphic creation.
Zeplin is a leading design handoff and collaboration platform that helps designers and developers deliver products efficiently.
Abstract is a version control platform for designers, bringing Git workflows to Sketch file management.