Onboarding external collaborators: tools and tips?

I wonder how do you guys organize "onboarding" for external collaborators on remote teams, which tools do you use for coordination, project management, talk, chat and screen sharing.

My tips, mostly free:

• talk/chat: skype, but mostly slack. Free tier is enough to start work with it, can be accessed from people outside of any organization (huge plus, no IT department involved)
• project management: jira/gitlab. Tools with huge differences, I know, but again huge boost to organize stuff, what to work, indipendently from your work method (waterfall or agile of any kind) and also for time tracking/estimation
• screen sharing: I've used hangout/skype/zoom/daily mostly, and I think daily as extension in slack, quickly create temporary room to share scren for many people is a plus ( and free )
• knowledge management: gitlab wiki, jira confluence. A space where store more than a chat, more than an issue, some kind of project "high level" documentation

What tools do you use? Do you have suggestions ?