Run Java applications
in the browser

No plugins. No desktop installs. No application rewrite required.

POWERING ENTERPRISE SOFTWARE

Your Java applications still work.

CheerpJ makes sure they keep working.

Rewriting critical systems is expensive, risky, and rarely necessary. CheerpJ runs Java applications in the browser, preserving your investment while simplifying deployment.

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https://apps.company.com/forms/ap_invoice.fmx?runtime=cheerpj

Oracle Forms Services - Accounts Payable

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Invoice Workbench

Invoice Approval

Session: FIN-OPS-2048

Supplier

Northbridge Industrial Components Ltd

Invoice Number

INV-104893

Invoice Date

16 Mar 2026

Currency

GBP

Description

Monthly hardware maintenance contract and replacement parts for regional branch systems.

Line	Cost Centre	Description	Amount	Status
001	FIN-221	Maintenance services	£31,200	Validated
002	OPS-118	Replacement hardware	£9,880	Validated
003	IT-074	Shipping	£1,500	Pending

Loading Oracle Forms

Java application running in browser via CheerpJ

72%

CJ

CheerpJ is loading Oracle Forms

Initializing Java runtime, loading application classes, and starting the Oracle Forms session directly inside the browser.

Loading runtime and application assets 72%

ARCHITECTURE

How CheerpJ runs Java applications in the browser

CheerpJ runs standard Java applications directly in the browser using WebAssembly. It provides a full OpenJDK runtime and Java Virtual Machine that executes Java bytecode without plugins, desktop installations, or source code changes.

1. Java Runtime in the Browser

CheerpJ includes a full OpenJDK runtime compiled to WebAssembly and JavaScript. It supports Java 8, Java 11, and Java 17 applications and runs entirely inside modern browsers.

3. Interpreter + JIT Optimization

Java bytecode starts in an interpreter, while frequently used code is compiled Just-in-Time into optimized JavaScript for higher performance.

2. JVM Executes Java Bytecode

Applications are loaded as standard JAR, class, or WAR deployments. CheerpJ executes the bytecode using a browser-based Java Virtual Machine.

4. Browser Integration Layer

CheerpJ provides system services needed by enterprise applications, including virtual file system support, HTTP networking, Java ↔ JavaScript interoperability, and AWT/Swing rendering through HTML Canvas.

PLATFORM SUPPORT

Enterprise Java compatibility

CheerpJ provides a browser-based JVM built on OpenJDK, with full Java language compatibility and bytecode-level execution. Supports standard JAR and WAR deployments, including Swing and AWT applications, without requiring a client-side JVM.

Java Versions

✔️ 8, 11, 17 (preview)
✔️ Java bytecode execution in the browser
✔️ Full Java runtime delivered client-side (WebAssembly-based)
✔️ Use for long-running applications that are difficult to rewrite

UI and graphics

✔️ Standard Swing/AWT widgets
✔️ Multiple windows within the application UI
✔️ Typical enterprise UI workflows (forms, tables, dialogs)

Networking

✔️ HTTP/HTTPS networking
✔️ Backend services remain unchanged
✔️ Works with existing application APIs and service endpoints

Deployment

✔️ On-premise
✔️ Controlled enterprise environments

Client results

Modernised a flagship Java application without a rewrite

A Fortune 500 HR software company used CheerpJ to modernise its flagship Java application for browser delivery while preserving most of its existing codebase.

01 Majority of Java code preserved

02 Reduced release effort

03 Eliminated duplicate codebase

Read the full case study

Evaluation process

How to
Evaluate
CheerpJ

Validate browser compatibility, runtime behaviour, and deployment requirements before production rollout.

Request a Compatibility Review

01

Input

Share application details

Java version, deployment model, UI framework, dependencies, authentication, and browser requirements.

02

Review

Compatibility review

Runtime, networking, security, file access, native dependencies, and JNI assessment.

03

Validation

Technical validation build

Test startup behaviour, workflows, authentication, browser support, and deployment requirements.

04

Deployment

Production deployment

Move into rollout planning, user acceptance testing, hosting, security review, and production support.

Request a demo

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.

Fill in the form or book a demo directly here

RESOURCES

Run Java applications
in the browser

Your Java applications still work.

CheerpJ makes sure they keep working.