drawnix

Drawnix is a free whiteboard in your browser for mind maps, flowcharts and freehand sketches. Nothing to sign up for: open drawnix.com and start drawing, and everything saves in your browser. It can also turn Mermaid code into a flowchart and a Markdown outline into a mind map, which is the feature to try first. MIT, backed by PingCode, the company behind the Plait drawing framework it's built on.

Self-hosting is a Docker image or a static build, so there's no backend to babysit. Exports cover PNG, JPG, SVG and its own .drawnix file. The toolbar has shapes, straight, curved and elbow arrows, text, pen, eraser and images, plus six color themes.

Solo users who think in mind maps: it fits better than excalidraw/excalidraw, which is freeform first. Teams that need to draw together live should stick with Excalidraw or tldraw/tldraw, because Drawnix has no real-time collaboration.

The catch is pace and storage. Releases are slow, seven months between the last two, and browser storage means clearing your site data can wipe your boards. Export anything you care about.