It's open source and is quickly surpassing GlassWire's capabilities.
Disclaimer: I'm Founder/CTO of Safing.
- The firewall itself with rules, filter lists, and so on - https://safing.io/features/
- Secure DNS (DoT/DoH resolver) - https://safing.io/features/
- "SPN": Optional paid VPN alternative similar to Tor, our source of revenue - https://safing.io/spn/