FortiOS is described as 'Fortinet FortiOS, an operating system underpinning Fortinet Security Fabric, is a solution designed to improve enterprise security, covering endpoints, cloud deployments, and centralized networks' and is a operating system in the security & privacy category. There are five alternatives to FortiOS for Linux and Self-Hosted. The best FortiOS alternative is CentOS, which is both free and Open Source. Other great apps like FortiOS are Red Hat Enterprise Linux, Rocky Linux, SUSE Linux Enterprise and Oracle Solaris.