Comparing Tomcat and Undertow in SpringBoot: Configuration, Performance, and Memory Usage

SpringBoot uses an embedded Tomcat container by default, but it also supports the Undertow container, which can offer better performance and lower memory usage.

SpringBoot Tomcat container : Tomcat is the default lightweight servlet container in SpringBoot, providing built‑in HTTP server capabilities and easy integration.

SpringBoot setting Undertow : By adding the Undertow dependency to the project (see the dependency diagram image), developers can switch the embedded server from Tomcat to Undertow with minimal configuration.

Undertow is a flexible, high‑performance Java web server that supports both blocking and non‑blocking I/O, full servlet and WebSocket support, and excels under high concurrency.

Tomcat vs. Undertow comparison : Tomcat is a widely used servlet container with its own HTTP server, while Undertow, developed by Red Hat, is a pure Java server designed for embedding and high throughput.

Performance test results (QPS):

Undertow shows higher QPS than Tomcat under the same hardware configuration.

Memory usage comparison :

Undertow consumes less memory than Tomcat while delivering superior throughput.

Overall, for high‑concurrency business scenarios, Undertow outperforms Tomcat in both performance and memory efficiency, making it the recommended choice.

Conclusion : SpringBoot allows using either Tomcat or Undertow as the HTTP server; however, Undertow is preferable for high‑traffic applications due to its better performance and lower resource consumption.