The best free alternative to pfSense is OPNsense, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 10 alternatives to pfSense and 16 is free so hopefully you can find a suitable replacement. Other interesting free alternatives to pfSense are NethServer (Free, Open Source), IPFire (Free, Open Source), ClearOS (Free, Open Source) and ZeroShell (Free, Open Source).
OpenContrail is an Apache 2.0-licensed project that is built using standards-based protocols and provides all the necessary components for network virtualization–SDN controller, virtual router, analytics engine, and published northbound APIs.
The securityrouter.org project is a network operating system and software distribution based on OpenBSD, featuring a single, revision-managed, clear-text configuration file with soft re-configuration, editable from CLI and web interface.