Java Virtual Machine for modern web browsers
CheerpJ is a WebAssembly-based Java Virtual Machine for the browser. It has extensive compatibility with Java 8 and provides a full runtime environment1 for running Java applications, applets, libraries, and Java Web Start / JNLP applications in the browser without plugins.
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With CheerpJ, you can:
- Run existing Java applications in the browser with no changes
- Include Java applets in webpages without legacy plugins
- Migrate Java Web Start / JNLP applications to work on modern systems
CheerpJ is based on a full OpenJDK runtime environment. It supports reflection, custom classloaders, networking, file access, clipboard, audio, printing, Swing, and AWT.Get started
Know what you’re building? Jump straight to the relevant tutorial:
How does CheerpJ work?
CheerpJ is a combination of two components:
- A full Java SE 8 runtime based on OpenJDK.
What’s unique about CheerpJ?
- CheerpJ can handle 100% of Java 8, including Swing, reflection and dynamic class loading with no manual intervention on the code.
- CheerpJ works directly on Java bytecode, and does not require access to the Java source code.
- CheerpJ comes with a full Java SE runtime, inclusive of Swing/AWT. It supports audio, printing, and any other Java SE features. The runtime supports WebAssembly for optimal performance and size.
- CheerpJ supports Java multi-threading. In addition, you can create concurrent applications by using Web Workers.
CheerpJ is free for personal use and technical evaluation. See licensing for details.
Several demos of CheerpJ can be found here.
You can also see CheerpJ in action in JavaFiddle:
CheerpJ is used in production by teams at NASA, Siemens, UBS, and many others.
There are several community projects that use CheerpJ, such as:
A board game playing application using AWT. Over 100 games are available to play against human and robot opponents using WebSockets.
A library providing bindings to common Web/DOM APIs for CheerpJ.
We have a vibrant Discord community where you can ask questions, share your projects, and get community support.Join our Discord server Follow us on Twitter
CheerpJ has been tested on Oracle Forms, EBS, Swing, AWT, and numerous frameworks and libraries. It should be able to run Java SE applications that you would otherwise need a Java Runtime Environment for. ↩