I think I have seen @scottalanmiller mention on here that he uses rocket chat for customers and for support. I had some questions comparing it to slack...
1.) Is it FOSS, download and host yourself for free?
2.) Is installing/managing it easy and low maintenance?
3.) Can a single install host multiple tenants
4.) Going with their hosting, can a $50 instance host mulitple tenants?
5.) How does this compare to just the free version of slack?