Processon
Online Mindmap, FlowChart, MindMap, UI, UML and Network charts with Collabration in Real-time.
Free plan
Web
Alternatives to Lucidchart
3 tools researchers use instead of Lucidchart. Open-source and free tools come first.
Whimsical
Visual workspace, online tool for quick diagrams
Free plan
Web
Computer Science
Gliffy
Diagram software that works as hard as your team.
Paid
Web
Prices and licences change, so check each tool's site. Missing one? Suggest a tool.