Who's actually using open source tools in their enterprise environment?

How many of you actually work with deployments of freeware/open source tools in your professional life?

In my experience a huge majority of enterprise environments rely on expensive software vendors for their security appliances. They're picking Palo Alto over PFsense for example.

Based on my searches on Reddit most "pro" IT subreddits suggest exclusively expensive vendor appliances. While IT hobbyist subreddits suggest open source and freeware (obviously they don't have the money to buy from the vendors).

I'm interested to …

cybersecurity enterprise environment open source open source tools tools