Tomcat is the servlet container that is used in the official Reference Implementation for the Java Servlet and JavaServer Pages technologies. The Java Servlet and JavaServer Pages specifications are developed by Sun under the Java Community Process.

Tomcat is developed in an open and participatory environment and released under the Apache Software License. Tomcat is intended to be a collaboration of the best-of-breed developers from around the world. We invite you to participate in this open development project. To learn more about getting involved, click here.

For the impatient, current Tomcat production quality releases vs. Servlet/JSP specifications:

Servlet/JSP Spec	Tomcat version
2.4/2.0	5.0.28
2.3/1.2	4.1.30
2.2/1.1	3.3.2

The releases are described in more detail below to help you determine which one is right for you. More details about each release can be found in the associated release notes.

Please note that alhough we offer downloads and documentation of older releases, such as Tomcat 3.x and 4.x, we strongly encourage users to use the latest stable version of Tomcat whenever possible. We recognize that upgrading across major version may not be a trivial task, and some support is still offered on the mailing list for users of old versions. However, because of the community-driven support approach, the older your version the less people would be interested or able to support you.

Tomcat 5.x

Tomcat 5.x is the current major release of Tomcat, and builds upon the Tomcat 3.3 and Tomcat 4.1 codebases. The 5.x releases implement the Servlet 2.4 and JSP 2.0 specifications. Tomcat 5.5.x. Tomcat 5.5 is the next branch in the Tomcat 5.x major release. While it supports the same Servlet and JSP Specification versions as Tomcat 5.0.x, there are significant changes in many areas under the hood. Please refer to the Tomcat 5.5 Changelog for details. Tomcat 5.0.x. Tomcat 5.0 improves on Tomcat 4.1 in many ways, including: Performance optimizations and reduced garbage collection Refactored application deployer, with an optional standalone deployer allowing validation and compilation of a web application before putting it in production Complete server monitoring using JMX and the manager web application Scalability and reliability enhancements Improved Taglibs handling, including advanced pooling and tag plugins Improved platform integration, with native Windows and Unix wrappers Embedding of Tomcat using JMX Enhanced Security Manager support Integrated session clustering Expanded documentation

Tomcat 4.x

Tomcat 4.x implements a new servlet container (called Catalina) that is based on completely new architecture. The 4.x releases implement the Servlet 2.3 and JSP 1.2 specifications. We encourage all users to upgrade to Tomcat 5.x whenever possible. Tomcat 4.1.x. Tomcat 4.1 is a refactoring of Tomcat 4.0.x, and contains significant enhancements, including: JMX based administration features JSP and Struts based administration web application New Coyote connector (HTTP/1.1, AJP 1.3 and JNI support) Rewritten Jasper JSP page compiler Performance and memory efficiency improvements Enhanced manager application support for integration with development tools Custom Ant tasks to interact with the manager application directly from build.xml scripts Tomcat 4.0.x. Tomcat 4.0.6 is the old production quality release. The 4.0 servlet container (Catalina) has been developed from the ground up for flexibility and performance. Version 4.0 implements the final released versions of the Servlet 2.3 and JSP 1.2 specifications. As required by the specifications, Tomcat 4.0 also supports web applications built for the Servlet 2.2 and JSP 1.1 specifications with no changes. We encourage all users to upgrade to Tomcat 5.x whenever possible.

Tomcat 3.x

There are several versions of Tomcat 3.x currently available for download: Version 3.3 is the current production quality release for the Servlet 2.2 and JSP 1.1 specifications. Tomcat 3.3 is the latest continuation of the Tomcat 3.x architecture and it is more advanced then 3.2.4, which is the 'old' production quality release. Version 3.2.4 is the 'old' production quality release and is now in maintenance only mode. Version 3.1.1 is a legacy release. All Tomcat 3.x releases trace their heritage back to the original Servlet and JSP implementations that Sun donated to the Apache Software Foundation. The 3.x versions all implement the Servlet 2.2 and JSP 1.1 specifications. Tomcat 3.3.x. Version 3.3.2 is the current production quality release. It continues the refactoring that was begun in version 3.2 and carries it to its logical conclusion. Version 3.3 provides a much more modular design and allows the servlet container to be customized by adding and removing modules that control the processing of servlet requests. This version also contains many performance improvements. Tomcat 3.2.x. Version 3.2 added few new features since 3.1; the major effort was a refactoring of the internals to improve performance and stability. The 3.2.1 release, like 3.1.1, was a security patch. Version 3.2.2 fixed a large number of bugs and all known specification compliance issues. Version 3.2.3 was a security update that closes a serious security hole. Version 3.2.4 is a minor bug fix release. All users of Tomcat versions prior to 3.2.3 should updgrade as soon as possible. With the exception of fixes for critical security related bugs, development on the Tomcat 3.2.x branch has stopped. Tomcat 3.1.x. The 3.1 release contained several improvements over Tomcat 3.0, including servlet reloading, WAR file support and added connectors for the IIS and Netscape web servers. The latest maintenance release, 3.1.1, contained fixes for security problems. There is no active development ongoing for Tomcat 3.1.x. Users of Tomcat 3.1 should update to 3.1.1 to close the security holes and they are strongly encouraged to migrate to the current production release, Tomcat 3.3. Tomcat 3.0.x. Initial Tomcat release. We encourage all users to upgrade to Tomcat 5.x whenever possible.