What are lightweight alternatives to Apache Tomcat?

If you're looking for lightweight alternatives to Apache Tomcat for hosting Java applications, there are several options to consider. These alternatives are known for their simplicity, fast startup times, and lower resource consumption. Here are a few lightweight servlet containers and application servers:

1. Jetty:

   • Jetty is a lightweight, embeddable web server and servlet container. It is often used for development and testing and is known for its fast startup times. Jetty can be embedded in applications or run as a standalone server.

2. Undertow:

   • Undertow is a lightweight, high-performance web server that is part of the WildFly application server. It can also be used as a standalone server. Undertow is designed to be flexible and efficient, making it suitable for various use cases.

3. Tomee:

   • Apache TomEE is a lightweight, yet full-featured, Java EE application server that builds on top of Tomcat. It provides additional enterprise features beyond what Tomcat offers while maintaining a focus on simplicity and ease of use.

4. Grizzly:

   • Grizzly is an NIO framework and web server that can be used for building scalable and high-performance web applications. It's often used as an embedded server and can be integrated into Java applications.

5. WildFly Swarm:

   • WildFly Swarm is a framework for building microservices and lightweight Java EE applications. It allows you to create custom runtime configurations based on your application's specific needs, including only the necessary components.

6. Spring Boot:

   • While not a traditional servlet container, Spring Boot is a popular framework for building Java applications, including web applications. It comes with an embedded Tomcat, Jetty, or Undertow server by default, making it easy to create standalone and lightweight applications.

When choosing a lightweight alternative, consider your specific requirements, such as ease of use, startup time, resource consumption, and the level of support for the features you need. Each of these options has its strengths and may be more suitable for different use cases.