A FreeRADIUS developer builds and maintains applications related to the FreeRADIUS software, an open-source protocol providing centralized network authentication. They create custom modules, debug issues, and ensure seamless integration with other systems. They work with protocols like RADIUS, HTTP, DHCP, and LDAP. Their job also involves configuring and managing FreeRADIUS servers, testing its security, and optimizing its performance. They work closely with network engineers to implement network access policies. Being knowledgeable in languages such as C and Python, and understanding network protocols, Linux administration, and database technologies are crucial for a FreeRADIUS developer.