In any collaborative environment, it's important to have good tools for communication.
What tools work best for you depends a bit on your situation, but might include anything from mailing lists for email communication, Git or Subversion for version control, a wiki or Etherpad for collaborative authoring, a shared task list for organizing workflow, or even a full fledged project management suite.
Internet Relay Chat, or IRC, is a protocol which dates back to the late 1980s.
Since it's been around so long, there are numerous open source implementations on both the client and the server side.
If you work with sensitive information or need to make sure that all communication stays behind a firewall, self-hosting might be your best option.
And access to the source helps you ensure that the communication between you and your team isn't seeping out of your control through some nefarious addition to the codebase.
You didn't think we'd be able to start this list off without talking a little more about IRC, did you?
access list kan typen, waarbij dat voorheen steeds met /msg Chan Serv access list moest.
Je kan instellen dat je kanaalbot in je kanaal blijft, ook wanneer je kanaal leeg is.
Personally, I find it too easy to be distracted by non-work conversations when I reuse the chat feature of, say, a social media tool.
I like to keep work separate so I can turn off personal communications when I'm at work, and vice versa. Slack quickly became the darling of software development circles, leading to the displacement of many other tools.