Best Authentication Software for C

​FreeRADIUS is a high-performance, modular, and feature-rich open source RADIUS suite that includes a server, client library, development libraries, and numerous additional utilities. It is the most widely deployed RADIUS server globally, powering major Internet Service Providers and telecommunications companies, and serving as a key technology behind eduroam, the international Wi-Fi education roaming service. FreeRADIUS supports a comprehensive range of authentication protocols, including PAP, CHAP, and all EAP types such as EAP-TLS, EAP-TTLS, and EAP-PEAP with EAP-MSCHAP. Its modular design allows for flexible configurations, enabling conditional request processing, integration with LDAP and SQL databases, and execution of external scripts. It supports virtual servers, simplifying complex implementations and reducing maintenance costs. With support for over 100 vendor-specific attributes, FreeRADIUS ensures compatibility with a wide array of network access servers.