What are some alternatives?
When comparing Filseclab Personal Firewall and Agnitum Outpost Firewall, you can also consider the following products
TinyWall - Lightweight and non-intrusive firewall
Windows Firewall Control - Windows Firewall Control is not the built in firewall system in the Windows operating systems.
Little Snitch - Little Snitch is a firewall application that monitors and controls outbound internet traffic.
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.
Windows 10 Firewall Control - Windows 10 Firewall Control: simple and exhaustive solution for applications network activity controlling and monitoring.
OpenSnitch - OpenSnitch is a GNU/Linux port of the Little Snitch application firewall.