The submitter extension allows for easy submission of BlueJ projects to another server or via email. Documentation is available on how to use the extension.

An extension to allow direct invocation of a main method. If a class contains a properly declared main method, this extensions adds a menu item "Run Main Method" which directly invokes it. This makes the main method much more obvious, if that suits your style, and also helps you get the declaration right; if it's not public static void main(String [] args) you won't see the menu item.
Note that calling the main method via this extension will restart the BlueJ "user" virtual machine (and therefore will remove all objects from the BlueJ object bench).
This extension is working with BlueJ 5.3.0 onwards.

An improvement over the original UML Extension, this one allows you to show more than one class display, and to move class displays around the screen. Available in English and German.

The PMD Extension for BlueJ is a wrapper for the open source code analysis utility PMD.

This extension gives the BlueJ user a handy way to quickly run the PMD source code analyzer on a Java class in BlueJ. It adds a PMD menu item to the BlueJ class menu. PMD finds common programming flaws like unused variables, empty catch blocks, unnecessary object creation, duplicated code, and so forth. This extension works with any version of PMD and works under Linux or Windows.

This extension adds an ‘About…’ item to the Tools menu to show you the locations of open projects and let you browse to their folders, also the last date modified of java files in the projects.

Supports automatic generation of getter and setter methods, as well as a GUI dialog to use these methods to edit an object's state.

Update from the original extension: displays a simple popup for a BlueJ class in the form of a UML Class icon. Details of what will be displayed, and the precise syntax used can be configured via the preferences panel, or the BlueJ properties files. New functionality: drag icons and double click event to close window.

Extension that enables creating and opening fxml files with Gluon SceneBuilder.

CheckStyle is a BlueJ extension that allows you to use the Checkstyle source code analysis tool. The user is provided the ability to choose what Checkstyle configuration file to use.

SonarLint is a BlueJ extension that introduces the SonarLint code analysis tool to BlueJ. (Java only) The plugin provides clear feedback with remediation guidance on flaws such as code smells, bugs and security vulnerabilities.