1: Free online drawing, no registration required
Support flowcharts, mind maps, Gantt charts, topology diagrams, sequence diagrams, prototype diagrams, UML, graphic design diagrams, circuit diagrams, etc.
https://www.iodraw.com/
Two: Free online flow chart mind map
A professional and powerful drawing tool that supports real-time online collaboration among multiple people and can be used to draw various graphics such as prototype diagrams, UML, BPMN, and network topology diagrams
https://www.processon.com/