Companies generally hire seasoned GDS & API developers because of various reasons such as experience, flexibility, availability, good communication and most important is their understanding of travel and hospitality domain. You must hire API developer either from top portals or from companies having over 10 years of experience in this field. The GDS API developer should have real-time experience on GDS like Amadeus, Travelport, Sabre and framework such as core data, familiarity with RESTful APIs to connect application, knowledge on UI/UX, understanding of code versioning tools such as Git, Mercurial or SVN.