One tiny shortcoming: Cyclic graph cannot be create (view is ok) on iOS platform but can be done on other platforms. Acyclic is a given.

One great feature is when it gets too big, graft-and-paste to a separate document is available.

Collaboration between devices of same account is excellent.

Disclaimer: not affiliated with XMind.

https://XMind.net

Some graph example on malware, anti-virus, and Trojans not created by me: https://www.xmind.net/m/VipY/

https://www.mindmeister.com/

I did a research recently and settled with xmind but I don't really like it.

I'm definitely gonna try whiscal.

That was so close (to supporting all major platforms). XMind can do it all.