I especially like Firebase tutorials and docs. After finishing tutorial on Firebase first launch I immediately knew where and how can I use Firebase in the future. When the time came we used it for real-time worker/web-app communication at http://dubjoy.com/ and it worked like a charm. I still don't know how to use web sockets and I hope I never will :) While working with Firebase we needed some ACL-like security features and Firebase delivered again. Amazing.
