draw.io is free online diagram software for making flowcharts, process diagrams, org charts, UML, ER and network diagrams

Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.

Coggle is a collaborative mind-mapping tool that helps you make sense of complex things. Create unlimited mind maps and easily share them with friends and colleagues.

Millions of people use XMind to clarify thinking, manage complex information, run brainstorming and get work organized.