StarUML

StarUML is compatible with UML 2.x standard, and supports in total 11 kinds of UML diagrams: class, object, use-case, component, deployment, composite structure, sequence, communication, statechart, activity, and profile diagrams. You can also create Entity-Relationship Diagrams (ERD). ERD is one of the most frequently used diagram for database modeling. Our ERD is based on crow’s-foot notation, which is much easier and readable than Chan’s notation.

• Creating elements and connecting them are somewhat tedious tasks. StarUML 2 supports many shorthand styles in Quick Edit to create elements and relationships at once such as sub-classes, supporting interfaces, etc.
• StarUML 2 supports Retina (High-DPI) display. All diagrams, texts and icons are razor sharp. You can also get diagrams as the high-dpi bitmap images (PNG and JPEG).
• You can easily find and install extensions via Extension Manager from the official extension registry or Github repositories. Many extensions are open source and hosted on Github. Fork one and make your own.
• StarUML stores models in a very simple JSON (JavaScript Object Notation) format. It can be used easily--in conjunction with mdgen, a command-line tool for custom-code generation based on EJS (Embedded JavaScript) templates--to generate custom codes using user-defined templates.