Toolabs DSM - Design System Manager plugin for creating themeable designs
UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.
Evie by unDraw - MIT licensed illustrations for your next project
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Haiku - Haiku is an open source OS catered specifically to the needs of personal computing.
Moqups - The most stunning HTML5 app for creating resolution-independent SVG mockups, wireframes & interactive prototypes for your next project