Flock is a communication-focused Slack alternative

Easy to use interface
Neat productivity tools
Free to use

Flock is another application very similar to Slack but is arguably a little less daunting to use and offers more comprehensive communication tools.

Flock supports channels for different teams as well as 1:1 or group conversations. Users can search through messages, files and links and Flock will find it no matter who sent it and where.
flock
There are audio and video calls and screen sharing as well as productivity tools such as polls, note sharing and reminders, while users can assign tasks to certain members of the group.

There’s also integrations with third party applications like Google Drive and Twitter, with notifications appearing directly in channels.

Flock is free to use, but searches are limited to 10,000 messages, there is a 5GB storage limit and only five third party integrations are permitted. A Pro plan adds unlimited search, 10GB of storage per user, and admin controls, while the Enterprise plan ads 20GB of storage per user, more admin controls and dedicated support.