Once a month an “insert something tech-related here” company releases an open source slack clone.

While I am grateful to all you guys, how much free time do you have to work on these clones instead of your main product?

I've tried so far let's chat and rocketchat and I liked them. I will give a spin to mattermost and I am sure I will like it too. I think the one that matures first, will be a big hit because we need a slack clone —as evidently shown. But also as with any other open source / free software project it will need commitment.