| Letter | App | Description | Platform | Download |
|---|---|---|---|---|
| # | ||||
| A | AFWall+ | AFWall+ (Android Firewall +) - iptables based firewall for Android | Android | Official repo |
| B | ||||
| C | ||||
| D | ||||
| E | ||||
| F | ||||
| G | Gufw | Gufw is an easy, intuitive way to manage your Linux firewall | Android | Official website |
| H | ||||
| I | ||||
| J | ||||
| K | ||||
| L | LuLu by Objective-See | LuLu is the free, shared-source macOS firewall that aims to block unknown outgoing connections unless explicitly approved by the user | Mac | Official website |
| M | ||||
| N | NethServer | NethServer is a CentOS-based Linux distribution for servers | Linux, CentOS | Official website |
| Nmap | Extensible, open-source network mapper with OS detection to scan networks for hosts and services | Windows, Mac, Linux | Official website | |
| O | OPNsense | OPNsense includes most of the features available in expensive commercial firewalls, and more in many cases | Self Hosted | Official website |
| P | Portmaster | Portmaster is a free and open-source application firewall that puts you back in charge over all your computer's network connections | Windows, Linux | Official website |
| Q | ||||
| R | ||||
| S | simplewall | Simple tool to configure Windows Filtering Platform (WFP) which can configure network activity on your computer | Windows | Official website |
| T | TinyWall | Lightweight and non-intrusive firewall | Windows | Official website |
| U | ufw | Ufw stands for Uncomplicated Firewall, and is program for managing a netfilter firewall. It provides a command line interface and aims to be uncomplicated and easy to use | Linux | Official website |
| V | ||||
| W | Windows Firewall Notifier | WFN is an "extension" to the embedded Windows firewall | Windows | Official repo |
| X | ||||
| Y | ||||
| Z |