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Grizzly NIO

Writing scalable server applications in the Java™ programming language has always been difficult. Before the advent of the Java New I/O API (NIO), thread management issues made it impossible for a server to scale to thousands of users. The Grizzly NIO framework has been designed to help developers to take advantage of the Java™ NIO API. Grizzly’s goal is to help developers to build scalable and robust servers using NIO as well as offering extended framework components: Web Framework (HTTP/S), WebSocket, Comet, and more!

Versions and Branches

  • 4.x.x : Next main version in development (Jakarta EE 10).
  • 3.x.x : This is the sustaining branch for 3.x (Jakarta EE 9). (latest release is 3.0.1)
  • 2.4.x : This is the sustaining branch for 2.4 (Jakarta EE 8). (latest release is 2.4.4)
  • 2.3.x : This is the sustaining branch for 2.3 (Java EE 8). (latest release is 2.3.35)

There are other branches for older releases of Grizzly that we don't actively maintain at this time, but we keep them for the history.

Getting Started


We have different JDK requirements depending on the branch in use:

  • JDK 11+ for master and 3.x.x.
  • Oracle JDK 1.8 for 2.4.x.
  • Oracle JDK 1.7 for 2.3.x.

Apache Maven 3.3.9 or later in order to build and run the tests.


See for the maven coordinates of the 2.3.x release artifacts.

If building in your local environment:

mvn clean install

Running the tests

mvn clean install


This project is licensed under the EPL-2.0 - see the LICENSE.txt file for details.