FreeRADIUS Server is the premiere open source RADIUS server. Based on current statistics, there are over 50,000 deployments of the software. These deployments include small sites with 10 users, large-scale enterprises with tens of thousands of users, and carrier-class deployments with over 10 million users. In total, the sites that we know are using FreeRADIUS support nearly 100 million users.

The server scales easily from embedded systems with small amounts of memory to systems with millions of users. It is fast, flexible, configurable, and supports more authentication protocols than most commercial servers. It includes support for SQL, LDAP, RADIUS Proxying, failover, load balancing, and nearly 100 vendor dictionary files. It can perform authentications via the PAP, CHAP, MS-CHAP, EAP-MD5, EAP-GTC, EAP-TLS, EAP-TTLS, PEAPv0, LEAP, EAP-SIM, and Digest authentication protocols.