JAX-RS 2.0 (JSR-339) and JAX-RS 2.1 (JSR-370), are JCP specifications that provide a Java API for RESTful Web Services over the HTTP protocol. RESTEasy is a portable implementation of these specifications which can run in any Servlet container. Tighter integration with WildFly application server is also available to make the user experience nicer in that environment. RESTEasy also comes with additional features on top of plain JAX-RS functionalities.