What are some alternatives?
When comparing Filseclab Personal Firewall and Little Snitch, you can also consider the following products
TinyWall - Lightweight and non-intrusive firewall
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.
OpenSnitch - OpenSnitch is a GNU/Linux port of the Little Snitch application firewall.
GlassWire - Visualize network activity in detail, get notified when new apps access the network, look out for...
simplewall - Simple tool to configure Windows Filtering Platform (WFP) which can configure network activity on...