FAI is described as 'Fully Automatic Installation, is a non-interactive system to install, customize and manage Linux systems and software configurations on computers as well as virtual machines and chroot environments, from small networks to large-scale infrastructures like clusters and cloud' and is an app in the os & utilities category. There are more than 10 alternatives to FAI for a variety of platforms, including Linux, Mac, Windows, BSD and Self-Hosted solutions. The best alternative is Ansible, which is both free and Open Source. Other great apps like FAI are Salt, Chef, Foreman and RunDeck.
Chef is an open source systems integration framework built to bring the benefits of configuration management to your entire infrastructure. You write source code to describe how you want each part of your infrastructure to be built, then apply those descriptions to your servers.
Bcfg2 helps system administrators produce a consistent, reproducible, and verifiable description of their environment, and offers visualization and reporting tools to aid in day-to-day administrative tasks.