• balsamiq for mocks
• slickplan.com for site map overview
• invisionapp for customer screen preview / review
• gliffy / yed for diagrams
• staruml for umls
• vym for mindmaps

you could use the adobe experience for the design prototyping as well

https://bootstrapstudio.io/
I will update with more soon. (Can't remember them.)

Update:
I was going to suggest pixate but they are saying farewell to it :/. It was amazing for prototyping on mobile!! There was another one as well for wireframing websites etc but I can't remember what it was - and I can't find it. Sorry! There is also https://www.xamarin.com/ which is awesome but not a fireframework i guess - but really cool still!

https://framerjs.com/ is really good - you use code to prototype :)

i use marvel , it small simple and forces to face your inefficient ,instead of a bunch of tools that sucking your intention and focus