Alternative of slack:
Today I met a friend of mine and he showed me this software hosted on his companies server. This is a great alternative for paid slack. We are using unpaid version of slack and some restriction like search limit no search functionality in archived history chat. Limitation on files shared are annoying. I don’t mean to say that I want all this free it is just that for us (trying not to pay for this) mattermost will be more suitable option.