BitBucket is freemium. You can have a personal account with an unlimited number of private or public repos for free. As soon as you start needing to share privileges with other users you need to pay up. JIRA and Confluence are definitely NOT freemium.
Confluence/JIRA if you're self hosting will set you back $10 for 10 users.
At that price point, some people are willing to fork out for that and set it up as a long running demo/test-case for a particular product without needing to get management/finance departments involved (which is often a stumbling block).
It's not 'freemium' but it's close enough.
That's usually enough of a wedge in the door to get management interested in a wider deployment.