Little Snitch - Little Snitch is a firewall application that monitors and controls outbound internet traffic.
Windows 10 Firewall Control - Windows 10 Firewall Control: simple and exhaustive solution for applications network activity controlling and monitoring.
Radio Silence - Radio Silence is a network monitor and firewall for the macOS. The software stops apps from making network connections. The firewall runs in the background and does not require an open window.
TinyWall - Lightweight and non-intrusive firewall
Hands Off! - Monitor your computer. Protect your privacy.
Emsisoft Online Armor Firewall - Emsisoft Online Armor Firewall is a freemium online firewall protection system by the Emsisoft that is based on the own independent protection technology of the Emsisoft.