Excalidraw

Excalidraw is an open-source virtual whiteboard for sketching hand-drawn-like diagrams. Its intentionally imperfect, hand-drawn aesthetic makes diagrams feel approachable and informal, perfect for brainstorming, architecture diagrams, wireframes, and technical illustrations. Despite looking casual, Excalidraw is packed with features: shapes, arrows with smart connectors, text, freehand drawing, image embedding, and a growing library of pre-made components. Real-time collaboration lets multiple people draw on the same canvas simultaneously. The tool works entirely in the browser with no account required, and you can save drawings as .excalidraw files or export to PNG and SVG. Excalidraw Plus adds persistent storage, team workspaces, and Excalidraw libraries. The community maintains thousands of reusable component libraries for architecture diagrams, UI wireframes, AWS infrastructure, and more. Excalidraw integrates with Obsidian, Notion, VS Code, and other tools through plugins. For developers, the React component is available as an npm package to embed whiteboarding directly into your application. The hand-drawn style has become a signature look in tech documentation and presentations across the industry.