Installing and Configuring JRebel for Hot Deployment in IntelliJ IDEA and Tomcat

When developing Java web applications, updating a class or Spring configuration traditionally requires restarting the Tomcat server, which wastes time; JRebel eliminates this delay by applying changes instantly.

JRebel can be installed in two ways: by adding its JVM arguments directly to Tomcat’s startup parameters, or by installing the JRebel plugin for IntelliJ IDEA (the recommended approach).

Method 1 – Adding parameters to Tomcat: Unzip JRebel to a local folder, then in IntelliJ IDEA open the Tomcat server configuration, select the Local server, and add a Deployment entry (preferably an exploded artifact). In the On 'Update' action and On frame deactivation fields choose Update classes and resources . Finally, add the appropriate VM options:

-noverify

Windows:

-agentpath:D:/dev_env/jrebel/jrebel_running/lib/jrebel64.dll

Linux:

-agentpath:/dev_env/jrebel/jrebel_running/lib/libjrebel64.so

macOS:

-agentpath:/dev_env/jrebel/jrebel_running/lib/libjrebel64.dylib

After saving the configuration, start Tomcat; the settings will be applied each time.

Method 2 – IntelliJ IDEA plugin: Install the JRebel plugin from a local archive, then enable it in the IDE settings. The plugin shows a green VALID status when active and adds two new green buttons next to the regular Run/Debug buttons. Ensure the same On 'Update' action and On frame deactivation options are set to Update classes and resources .

Custom container launch: The configuration is identical to Method 1, except the VM options field can be left empty; simply start the project using the Debug button.

Maven/Gradle integration: Open the JRebel panel, select the desired project or module, and the plugin will generate a rebel.xml file under src/main/resources that defines the hot‑deployment directories. Then run the project via the Maven or Gradle task; after changes, press Ctrl+Shift+F9 to recompile resources.

JRebel offers a free trial activation key on its official website; register there to obtain a license key.