Run Java in the browser

CheerpJ Core is a WebAssembly-based Java Virtual Machine for the browser. It has extensive compatibility with Java 8, Java 11 and Java 17 (preview), and provides a full runtime environment for running Java applications, applets, libraries, and Java Web Start applications in the browser without plugins.

It works directly with existing Java bytecode and JAR files, so teams can preserve access first and modernize on their own schedule.

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Key Features

Java on the browser

CheerpJ Core enables modern browsers to run Java 8, Java 11 and Java 17 preview client-side.

Full runtime

A full OpenJDK runtime environment is delivered client-side so existing applications can run with minimal change.

Scalable JNI architecture

CheerpJ has extensive native method compatibility and provides a viable path for running complex Java applications.

Networking and system access

HTTP(s), TCP/IP, file access, clipboard, printing, audio, and more are exposed through browser-safe integrations.

Java and JavaScript interoperability

CheerpJ provides multiple mechanisms for Java and JavaScript to interoperate inside the same browser application.

Full classloader support

Application-provided classloaders still control resolution, which helps preserve compatibility for sophisticated clients.

No source rewrite required

CheerpJ operates on bytecode and JARs, so third-party dependencies and obfuscated code are not blockers.

Legacy modernization

Teams can remove the dependency on IE, Edge IE mode, plugins, and local Java installations.

Library embedding

Java components can be brought into web-native applications alongside HTML, CSS, and JavaScript.

What You Can Run

Java Applications

Run full Swing and AWT clients in the browser using existing Java bytecode.

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Java Applets

Preserve legacy Applet-based applications without browser plugins.

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JNLP / Web Start

Modernize Java Web Start delivery without relying on a local desktop JVM.

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Java Libraries

Instantiate Java libraries or packaged JARs directly in the browser.

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Learn More About CheerpJ Core

Ready to evaluate CheerpJ Core?

We can help you validate compatibility, choose the right deployment model, and plan a low-risk migration path for existing Java clients.

Request a demo ›