Apache Tomcat

Definition

Apache Tomcat is an open-source Java Servlet container and web server that implements the Jakarta Servlet, JSP, and WebSocket specifications, used to deploy and run Java web applications.

Overview

Tomcat originated as the official reference implementation for Sun Microsystems' Servlet and JSP specifications before being donated to the Apache Software Foundation, where it has been maintained ever since as one of the most widely deployed Java web servers. Internally, Tomcat is organized around a few core components: Catalina, the servlet container that manages the request-processing lifecycle; Coyote, the HTTP connector that handles network communication; and Jasper, the engine that compiles JSP pages into servlets. Tomcat is lighter weight than a full Java EE application server, focusing on the web tier rather than the full enterprise Java stack. It's commonly deployed behind a reverse proxy like Nginx or Apache HTTP Server for load balancing and TLS termination, and applications built with Spring Boot frequently run on an embedded Tomcat instance rather than a separately installed server. Applications destined for standalone Tomcat are typically packaged as WAR files using build tools like Apache Maven, and Tomcat is routinely containerized with Docker for deployment. Despite the rise of embedded servers and cloud-native runtimes, Tomcat remains a dependable, widely understood option for hosting Java web applications and APIs.

Key Features

• Implements Jakarta Servlet, JSP, and WebSocket specifications
• Lightweight compared to full Java EE application servers
• Embeddable inside applications, notably Spring Boot
• Connector-based architecture (Catalina, Coyote, Jasper)
• Session clustering and replication support
• Extensive XML-based configuration
• Long track record of active security maintenance

Use Cases

Frequently Asked Questions

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