Mac OS X 10.7 Lion , Mac OS X 10.8 Mountain Lion , Mac OS X 10.9 Mavericks , Mac OS X 10.10 Yosemite , Mac OS X 10.11 El CapitanWindows XP , Windows Vista , Windows 7 (Seven) , Windows 8 , Windows 8.1 , Windows 10
This program is called "yEd Graph Editor". It is an easy-to-use tool for creating and editing diagrams. The program works much like many similar applications. You'll choose your symbols from a palette (flowchart, UML, ERD, BPNM, network, computer, more), drag and drop them onto the page, and position them as you like.
Symbols may then be customised with text, colours, URLs and more, before you join them up with lines to represent your structure or ideas.