You can run discourse in a container and the only real hassle is publishing your own version of the discourse app so you can get push notifications without having to pay them.

Zulip is also available as a container.

Not in my experience. We spent a nontrivial amount of time on running and maintaining our discourse instance - dev time that is very costly as a small company. Might be different at Posthog level of investment of course. That was about three years ago, so maybe running discourse is much easier now.

1. What forum did you use that turned into a lot of work?

2. What is the way around the free plan message limit?

3. What do you use Slack for?

1. Discourse. Might be different for others but I had 0 time to manage the deployment, and upgrades took a lot of time.

2. I used https://www.linen.dev/ but I think there are others. It turn Slack conversations in a searchable static site.

3. Developer community for an open source software product.