Dreamwidth has used a number of real-time chat methods over the years.
Discord: active, and official since December 2018
Slack: used briefly around 2015, no longer particularly active
IRC: Freenode, where some channels still exist but are no longer the official venue. Before that, a private server which used to also be the LiveJournal volunteer hangout.
Information to join is posted in dw_dev. New arrivals go to a welcome channel.
If you are a current or former developer or other volunteer, feel free to join. If you are curious about starting, you are also welcome.
Welcome: for new arrivals.
Volunteer: various topics
Off topic: things which aren't on topic
Development: various topics