Not sure what type of diagrams you are looking for, but PlantUML has a handwritten &#x27;skin&#x27; for the usual UML diagrams.<p><a href="http:&#x2F;&#x2F;plantuml.com&#x2F;handwritten.html" rel="nofollow">http:&#x2F;&#x2F;plantuml.com&#x2F;handwritten.html</a>