- Atlassian has more than 10x the revenue of Slack[1]
- JIRA and Confluence account for substantial amount of Atlassian's revenue. Two products that don't even compete with Slack[2].
I think Slack is a current silicon valley darling so people love to make this comparison but it doesn't directly compete with Atlassian's core business. It also has an order of magnitude less revenue.
[1] http://www.businessinsider.com/slack-expects-30-million-reve...
[2] https://www.sec.gov/Archives/edgar/data/1650372/000155837015...