Violet UML Editor!

Lucidchart is an online diagram and flowchart software that supports Microsoft Office Visio import and can work on any operating system. The easiest way to draw flowcharts, wireframes, UML diagrams, network diagrams, mind maps, iPhone mockups, site maps and more. Work together in real time with your team and clients! Along with the online version, Lucidchart also has a downloadable solution that runs on Mac, Windows and Linux; this enables offline editing at any time! »

Pencil is a standalone app or Firefox extension that lets you create diagrams or UI mockups. It doesn't have collaboration/multi-user features.

Lucidchart is an online diagram and flowchart software that supports Microsoft Office Visio import and can work on any operating system. The easiest way to draw flowcharts, wireframes, UML diagrams, network diagrams, mind maps, iPhone mockups, site maps and more. Work together in real time with your team and clients! Along with the online version, Lucidchart also has a downloadable solution that runs on Mac, Windows and Linux; this enables offline editing at any time! »

PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams. The generator can be run anywhere within JVM and integrated with various application such as wiki, text editor, IDE, programming language, documentation generator, and others. Mostly based on Graphviz. Can render various diagram syntax such as PlantUML, Dot, and Ditaa.

Axure RP is the leading tool for rapidly creating wireframes, prototypes and specifications for applications and web sites.

UMLet is an open-source UML tool with a simple user interface: draw UML diagrams fast, export diagrams to eps, pdf, jpg, svg, and clipboard, share diagrams using Eclipse, and create new, custom UML elements.

Visual Paradigm for UML (VP-UML) is a UML design tool and UML CASE tool designed to aid software development. VP-UML supports key modeling standards such as Unified Modeling Language (UML) 2.4, SysML, ERD, DFD, BPMN 2.0, ArchiMate 2.0, etc. It supports software development teams in requirements capturing, software planning (use case analysis), code engineering, class modeling, data modeling, etc.

Simple vector graphics editor for creating flowcharts, UML class diagrams, illustrations and slide shows.

Lightweight, powerful, easy to use, UML tool

Graphical modelling open source UML2 tool based on Eclipse environment.

ProcessOn provides an easier way to create diagrams.It's completely FREE OF CHARGE .Drag and drop shapes, icons and other usuful elements in your logic thinking or following your procedure, then optimize your diagrams’ color, style,so everyone even the beginner will become a diagram rockstar just in a minute.ProcessOn also has a diagram library where you can choose tons of shapes and objects then share them through social network. Templates included:-Flowcharts-BPMN-Value chain-ERD-UML-UI/IOS mockups-Org charts-Venn diagrams-MindmapProcessOn is also a professional social network, specially designed for digrammers, designers, consultants, IT engineers.You just can connect with the experts or influences in your professional field, in the meantime, you can rise your personal reputation as well.Here you wont’ miss the lastest trends in one’s specific field.Now we support 5 languages. »

WireframeSketcher is a software tool that helps quickly create wireframes, mockups and prototypes for desktop, web and mobile applications. It comes both as a plug-in for any Eclipse-based IDE and a standalone version. With WireframeSketcher users can quickly gather useful feedback from stakeholders, show off their proposals to clients, share their ideas with fellow developers and in the end build better software.

From free light-weight versions which provide Intuitive UML software at no cost; to the most powerful UML Plus software on the market Astah allows your team to communicate clearly and easily across platform. Take your Modeling to the next level with Astah.

NClass is a free tool to easily create UML class diagrams with full C# and Java language support. The user interface is designed to be simple and user-friendly for easy and fast development. Properties, enums, delegates and other language specific elements are fully supported with strict syntactical and semantical verification.

WhiteStarUML is a fork of StarUML with an intent to revive its Delphi code base by updating code to recent Delphi editions, reducing dependence on third party components and fixing bugs and adding new features.