Excalidraw

Excalidraw is a Czech virtual whiteboard for quick diagrams, wireframes, brainstorming, and lightweight presentations, built around a hand-drawn visual style. Its core editor is open source and local-first, with real-time collaboration, end-to-end encrypted share links, offline/PWA support, open `.excalidraw` files, and self-hostable code, while Excalidraw+ adds paid cloud workspace features for teams.