The complete Java runtime for modern browsers

CheerpJ is a JVM and distribution of OpenJDK for the browser in WebAssembly and JavaScript. Now supporting Java 8 and Java 11, with Java 17 coming in late 2025.

The complete Java runtime for modern browsers

CheerpJ is the only solution which can run any large-scale, unmodified Java applications, applets, or libraries in the browser. No downloads or plugins required.

Why choose cheerpj

Run Java on Modern Browsers

CheerpJ is a WebAssembly-based Java Virtual Machine and distribution of OpenJDK for modern browsers.

🎯Broad Compatibility – Supports Java 11, Java 8 and earlier. Java 17+ coming in 2025.

🖥️Rich UI Support – Runs Swing, AWT, Oracle Forms / EBS and most frameworks in the browser.

🔒Secure & Isolated – Runs fully within the browser sandbox, with no access to the host system.

🧰Full System Integration – Clipboard, networking, file access, customer native methods.

Not sure where to start?

Get Started Based on Your Role

Build with Java & WebAssembly
on modern browser.

Improve accessibility and eliminate
dependency on legacy Java setups.

Reduce rewrite costs and modernize
Java apps without code changes.

Run Legacy Java Applications in the Browser

CheerpJ lets you run Java Applications, Applets, and Java Web Start Applications directly in modern browsers — without a local Java installation.

It has extensive Java compatibility, ships a full OpenJDK environment, and supports Java UIs including Swing, Oracle Forms, EBS, and many other third-party frameworks.

By removing the need for Java installations and legacy browsers on the client, CheerpJ improves both accessibility and security of legacy systems.

Modernize Java Applications without a Rewrite

CheerpJ makes it easy to modernize existing Java apps to web standards — without changing any code.

It automates full migrations or accelerates partial migrations of existing Java clients into browser-based Web Apps. Extensive interoperability between CheerpJ and JavaScript enables gradual rewrites to Web-native technologies, while preserving critical existing components.

Powered by WebAssembly and modern browser technology, CheerpJ offers a unique path to the modernization of legacy Java.

Use Java in Modern Web Applications

CheerpJ allows web developers to run Java libraries in the browser, integrated in Web Applications.

By running Java components within the browser sandbox, developers can build a new generation of fully client-side Web applications that combine Web-native components with Java libraries to implement complex functionalities.

Built on WebAssembly, CheerpJ provides a full Java environment and OpenJDK compatibility to the browser.

CheerpJ: The JVM for Modern Browsers

200,000+
Users Worldwide
4.5★
Average Rating
>80%
Savings vs rewrite

Our Tools

CheerpJ Core

The main CheerpJ tool for developers. A JVM / OpenJDK distribution in JavaScript and WebAssembly. Runs full Java applications and libraries in the browser.

Use Cases:

🖥️Modernize legacy Java Desktop applications

📱Develop Web Apps with Java components

🎓Java educational platforms and training apps

🛠️Browser-based deployments of legacy internal software

 

CheerpJ JNLP Runner

An end-user tool to run Java Web Start apps in Chrome or Edge – without installing Java locally. Perfect for legacy enterprise applications.

Use Cases:

🧾Launch .jnlp  files in modern browsers

🏢Replace deprecated Java Web Start workflows

🧪Scientific and technical software delivery

🌐Support your enterprise migration to OpenJDK

CheerpJ Applet Runner

An end-user tool to run Java Applets on modern browsers. Works instantly on Chrome or Edge, no code changes required.

Use Cases:

🧱Access Applets onlegacy websites

💹Financial/trading platforms with applet UIs

🎓Educational tools, and scientific simulations

🌐Support your enterprise migration to OpenJDK

Not sure where to start? Find the right tool for you.

What’s Next for CheerpJ?

We’re building the future of Java in the browser. CheerpJ is an actively developed technology with an ambitious timeline for 2025 and 2026. Here’s what’s coming:

Feature Availability Status
Java 8 Support Available 🟢 Released
Java 11 Support Available 🟢 Released
Mobile Support Available 🟢 Released
WebAssembly JNI Modules Available in preview (on demand) 🟢 Nightly Builds
Java 17 Support Late 2025, in preview from May 2025 🟡 In Development
JavaFX Support Planned 🟡 In Development
Java 21+ Support 2026 🟡 In Development

Learn More About CheerpJ

Learn More About CheerpJ

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What People Think About Us

What People Think About Us

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Discover how to modernize and improve access to your legacy Java applications with CheerpJ.

Schedule a free demo with our team to learn how CheerpJ can help address your Java requirements.

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