Diagram

• draw.io
• Mermaid - markdown-inspired text to diagram
• D2 - diagramming language

Whiteboard

• Excalidraw (Canvas)
• tldraw (DOM)

Hand-drawn style

• Adding hand-drawn font for Chinese, Japanese and Korean to Excalidraw
• Hand-drawn diagram aesthetic

Library

Also fonts & icons

• Rough.js
• roughViz.js (chart)