Developing Restful JSON API fro, scratch is a complex task as it involves many different concepts such as HTTP request / response handling, content negotiation, data validation, data serialization, errors handling, etc. Fortunately, the PHP & Symfony ecosystems have Open-Source libraries such as API Platform to ease the development of Restful JSON Web services. API Platform is a framework for building Restful JSON API endpoint. It implements all common Rest architecture concepts and provides all necessary tools and configuration layers to Web developers, so that they can focus on the business logic of their APIs. In this workshop, attendees will get started with the API Platform framework and build their first Resftul JSON Web services for an existing application.