This talk is about how to secure your front-end + backend applications using a RESTful approach. As opposed to traditional and monolithic server-side applications (where the HTTP session is used), when your front-end application is running on a browser and not securely from the server, there are few things you need to consider. In this session Alvaro will explore standards like OAuth and JWT to achieve a stateless, token-based authentication and authorisation. He will explore the existing impl More specifically, the demonstration will be made using Spring Security REST, a popular Grails plugin written by Álvaro. Authentication is normally a stateful service. Most of the implementations rely on the HTTP session, thus introducing state as the session is an in-memory data structure in the application server. In the microservices era, most of the companies are developing such called RESTful services, where one of the principles is to create stateless systems. In such scenario, authentication should be stateless too. There is a standard specification to secure web application and API's, that is being adopted massively by the industry: OAuth 2. The specification doesn't explicitly cover how to make a stateless implementation. And most of the existing ones depend on some sort of external storage (such as a DB) to store the tokens generated for a later validation. Fortunately, there is another specification by the IETF called JSON Web Token, that can be combined with OAuth 2 to achieve a stateless authentication system. In the session, Alvaro will explain the core concepts of OAuth 2, as well as JWT and how can them be used together to achieve the last 2 letters of REST: State Transfer.