Ask HN: Any open source alternative to Slack?

We used a self-hosted version of RocketChat at my previous employer's.

This looks really good. I will try self hosting this!

i think matrix is a good alternative, after all, you can self-host it

It's super hard to self host...any other alternatives?

Matrix synapse server is hard to configure, if you don't need some features there are alternatives that need only an config file.

Mattermost is an opensource Slack clone.

Compared to Matrix/Synapse this is worlds easier to manage

I have no experience in what these systems look like when used at scale, only deployed for play, but I expect a simpler life with Mattermost

You might want to check out Mattermost! It's a great open-source alternative to Slack, offering similar features and functionalities.

zulip is another option

I've heard of many people trying out Zulip and actually preferring it to Slack at the end.

IRC