TinyWall - Lightweight and non-intrusive firewall
pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
GlassWire - Visualize network activity in detail, get notified when new apps access the network, look out for...
IPFire - IPFire is a server distribution with intended to use as a firewall.
Windows Firewall Control - Windows Firewall Control is not the built in firewall system in the Windows operating systems.
OPNsense - OPNsense® you next open source firewall. Free Download. High-end Security Made Easy™. Offers Intrusion Prevention, Captive Portal, Traffic Shaping and more.