Spring Boot provides WebSockets auto-configuration for embedded Tomcat, Jetty, and Undertow. If you deploy a war file to a standalone container, Spring Boot assumes that the container is responsible for the configuration of its WebSocket support.
Spring Framework provides {spring-framework-docs}/web.html#websocket[rich WebSocket support] for MVC web applications that can be easily accessed through the spring-boot-starter-websocket module.
WebSocket support is also available for {spring-framework-docs}/web-reactive.html#webflux-websocket[reactive web applications] and requires to include the WebSocket API alongside spring-boot-starter-webflux:
<dependency>
<groupId>javax.websocket</groupId>
<artifactId>javax.websocket-api</artifactId>
</dependency>