Summary: OPNsense is a free, open-source firewall and security platform offering features like Virtual Private Networking, Intrusion Detection, and more. It supports IPv4 and IPv6, multi-WAN, hardware failover, and web filtering. The user interface is available in multiple languages and offers two-factor authentication. OPNsense Business Edition provides additional commercial features and support. The Zenarmor plug-in extension enhances the platform with Threat Intelligence and next-generation firewall capabilities.