Reduce The Download Size of Java Applications

Excelsior JET is a certified Java SE 8 JVM with an Ahead-Of-Time (AOT) compiler and installation toolkit.


One of its unique features is the Java Runtime Slim-Down deployment model that enables you to bundle a light Java SE Runtime with your application to reduce the installation package size.

Available since 2007, Java Runtime Slim-Down has been proved effective for many Java applications. For GUI applications, in particular, the size of a complete installation package without dependency on the JRE starts from 5MB.

Watch a demo to see it in action

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Sample applications

The table below shows the download size figures for a few sample applications optimized using Java Runtime Slim-Down.

Note: the JRE need not be installed on end user systems to run these Java applications.

Application GUI toolkit Download Description
JavaCC none 3.9 MB The most popular parser generator for use with Java

SWT 4.6 MB Sample program taken from Eclipse SDK, illustrates common Standard Widget Toolkit (SWT) controls

Swing 8.7 MB Popular cross platform text editor

SWT+Java2D 9.4 MB Popular RSS/RDF/Atom Newsreader

Swing 9.0 MB Peer-to-peer tool to synchronize files between PCs in home-network, intranet or over the internet

SWT+Java2D 9.5 MB Multitrack guitar tablature editor and player. Check it with this evergreen opus. It will rock you!

Click a link in the "Download" column to download the installation package for Windows.


What Java SE components can be removed?

Some parts of the Java SE API are sufficiently isolated from the rest and can be removed altogether if the application does not use them.

The following components are supported by Java Runtime Slim-Down: AWT/Java2D, CORBA, JDBC, JNDI, JSound, Management, RMI, Swing, XML, and Scripting (Rhino Javascript engine in Java 7).

Each component may comprise:

  • public API classes
  • implementing classes (one or more packages)
  • native method libraries and associated resource files, such as fonts
Does it help reduce disk footprint of Java applications?

Yes, of course. For instance, look at disk space occupied by the installed sample applications listed above:

Application Disk Footprint Description
JavaCC 13.1 MB Parser generator for use with Java
SWTDemo 14.4 MB Sample with SWT controls
RSSOwl 33.4 MB RSS/RDF/Atom Newsreader
PowerFolder 33.4 MB Tool to synchronize files between PCs
TuxGuitar 31.1 MB Guitar tablature editor and player.
Sun JRE 5.0 Update 13 69.6 MB Included for reference, not required to run the other applications.
Sun JRE 6 Update 15 79.2 MB Included for reference, not required to run the other applications.

As you may see, the disk footprint of the optimized applications is much smaller that the footprint of the JRE alone.

When Java Runtime Slim-Down cannot help?

If your Java application contains tens of thousands of classes or large data files, Java Runtime Slim-Down may have only a minor impact on the size of the resulting installation package.

How does it compare to modularized JDK (Project Jigsaw)?

As modularized JDK is not yet ready (was scheduled for Java 7, then Java 8, but then postponed again), it cannot be compared to Java Runtime Slim-Down simply because what is planned and what will be finally implemented may differ.

Nevertheless, we believe that Project Jigsaw is a step in the right direction.