Open-source diagrams and whiteboards

4 diagrams and whiteboards whose code is public under an OSI-approved license, rated for privacy with evidence. Picks first, then by score.

1. draw.io Grade B

   An open-source diagramming app for flowcharts, UML, network and architecture diagrams that runs in the browser or as a desktop app, and saves files to the device or to a storage service the user chooses.

   Apache-2.0. Source code

2. Mermaid Grade B

   An open-source JavaScript library that renders flowcharts, sequence, class, Gantt and other diagrams from Markdown-like text definitions. It is built into many documentation tools and code hosting sites.

   MIT. Source code

3. Excalidraw Grade C

   An open-source virtual whiteboard for sketching hand-drawn style diagrams in the browser. Drawings are stored locally, and shared links and live collaboration are end-to-end encrypted. A paid hosted workspace, Excalidraw+, is also offered.

   MIT. The paid Excalidraw+ service is closed source. Source code

4. PlantUML Grade F

   An open-source Java tool that generates UML and other diagrams, such as sequence, class, activity, Gantt and mind maps, from plain-text descriptions. It runs locally or through a public or self-hosted rendering server.

   GPL-3.0, with builds also offered under GPL-2.0, LGPL, Apache-2.0, BSD, EPL-2.0 and MIT. Source code

Compare all 12 diagrams and whiteboards, open source or not.