GlassWire is a lot more than just a great firewall. The free firewall software monitors your network in an easy to understand way, watches for network related threats, and it lets you know any time something new on your computer is connecting to the Internet.
The free version of GlassWire is awesome, but the Pro version has a lot of extra features including the ability to see who is on your WiFi network, Allow/Deny new connections, and see when something on your PC tries to use your Mic or Webcam potentially spying on you.