Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Toolabs DSM - Design System Manager plugin for creating themeable designs
Invision - Prototyping and collaboration for design teams
Evie by unDraw - MIT licensed illustrations for your next project
Sketch - Professional digital design for Mac.
Haiku - Haiku is an open source OS catered specifically to the needs of personal computing.