APIs (Application Programming Interface) provide the ability to do what needs to be done. The fact that FOLIO includes API as one of its building blocks makes it that much more attractive. When my library’s administration decided to switch from a legacy ILS (Integrated Library System) to a FOLIO LSP (Library Services Platform) the first thing that I looked at was the API. The lessons learned helped me to configure the system and massage the data from ILS output to FOLIO-friendly input. By building web applications and writing Perl scripts our staff is able to get the job done even when it is impossible to accomplish the task through the user interface (UI).