Is React.js a library or a framework? In any case, it is a new way of working that represents a revolution in the way of building web projects. It has very particular characteristics that allow us, for instance, to render React code from the server side, or to include React components from Twig tags. During this talk we will present React.js, we will explore how to take advantage of it from PHP projects and we will give answers to practical problems such as universal (isomorphical) rendering and the generation of React.js forms from Symfony forms without duplication of efforts.