Astah Community is a free software design tool which supports the latest UML diagrams.

Cacoo is a user friendly online drawing tool. Multiple users editing the same diagram means Real-Time Collaboration.

ConceptDraw PRO is diagramming software used to create business graphics, including ConceptDraw Flowcharting Suite.

Creately is a collaborative diagramming and design software used by teams around the world to communicate more effectively.

Diagram Designer is a vector graphics editor that allows you to create UML class diagrams, illustrations, flowcharts and slide shows.

Diagrammix is a tool for efficiently building attractive diagrams and flowcharts.

bubbl.us is a mind map tool. It's a visual thinking tool for structuring information, helping you to better understand, remember and generate new ideas.

Coggle is a freeware mind-mapping web application. Like other mind-mapping software, Coggle produces hierarchically structured documents, like a branching tre…

ConceptDraw MINDMAP is a mind mapping and brainstorming software.

Dia is free and open source drawing software.

draw.io is free online diagram software for making flowcharts, process diagrams, etc

Diagramo is an online flowchart software. It's FREE and Open Source ( GPL ) It's pure HTML5 Share and collaborate.