mattermost

Install command: 
brew install --cask mattermost

Name: Mattermost

Open-source, self-hosted Slack-alternative

https://mattermost.com/

Cask JSON API: /api/cask/mattermost.json

Cask code: mattermost.rb on GitHub

Current version: 5.12.1

Current version requires: macOS >= 11

Versions:

Intel sequoia 5.12.1
sonoma 5.12.1
ventura 5.12.1
monterey 5.12.1
big sur 5.12.1

Analytics:

Installs (30 days)
mattermost 448
Installs (90 days)
mattermost 1,368
Installs (365 days)
mattermost 4,633
Fork me on GitHub