umlet

UMLet is a free, open-source UML tool with a simple user interface: draw UML diagrams fast, build sequence and activity diagrams from plain text, export diagrams to eps, pdf, jpg, svg, and clipboard, share diagrams using Eclipse, and create new, custom UML elements. UMLet runs stand-alone or as Eclipse plug-in on Windows, OS X and Linux. Also, check out our other tools, especially our new web-based UMLet, called UMLetino.