I have installed a program named Mattermost on my home server. I have been using it for a couple of weeks and it is very powerful. In my previous job, we used a similar program named Slack that we used extensively. Both of these are super-capable chat clients. I figured out how to do task lists in Mattermost. This is a life saver for a lot of the stuff I am doing.
I like Mattermost best because it is free at the low level I need, easy to use, I can run it on my home server, and it does everything I want it to do.