What is CheerpJ?

CheerpJ is a WebAssembly-based Java Virtual Machine for the browser. This means Java applications can be executed from the browser with no Java installation. It has extensive compatibility with Java 8, 11, and 17, providing a full runtime environment for running Java applications, applets, libraries, and Java Web Start / JNLP applications in the browser without plugins.

How it works

The magic behind CheerpJ is Cheerp, which was used for compiling full Java SE 8, 11, and 17 runtimes based on OpenJDK. This runtime was originally written in C++ and compiled to WebAssembly and JavaScript, making it 100% browser compatible. The architecture is designed to support multiple versions of Java, as well as custom runtimes.

What can CheerpJ run?

CheerpJ Core can run standalone Java applications, applets, JNLPs, and also in library mode. We have published two end-user-ready browser extensions based on CheerpJ technology: the CheerpJ Applet Runner and the CheerpJ JNLP Runner.

You can learn more about how to use CheerpJ in our documentation.