The CheerpJ browser extension for Java Web Start runs Java Web Start applications in the browser, with no Java installed on the computer. Open a .jnlp file and the application runs in a tab. It is listed as CheerpJ JNLP Runner in the Chrome Web Store and Edge Add-ons.

The extension replaces the Java Web Start client that Oracle removed from Java 11. It has been tested on Oracle E-Business Suite, Oracle Forms and hundreds of custom Java client applications. It is built on CheerpJ, a Java runtime built from OpenJDK and compiled to WebAssembly, and the CheerpJ browser extensions have more than 170,000 users together.

What it runs

• Java: Java 8 Web Start applications, with their Swing and AWT interfaces.
• Applications: Oracle E-Business Suite, Oracle Forms and custom Java clients.
• Browsers: Chrome, Edge and other Chromium browsers, on desktop.
• Files: upload files from the side panel; files the application saves arrive as browser downloads. See upload and download files.
• Networking: HTTP(S) through the browser. TCP and UDP sockets through a Tailscale network, set in the extension’s settings.

For Oracle Forms and EBS across an organisation, see Oracle Forms and Oracle EBS. To build with CheerpJ, see the CheerpJ documentation. For an applet inside a web page, use the extension for applets.

Getting started

1. Install the extension in Chrome or Edge.
2. Click a link to a .jnlp file, open one from your computer, or drag it onto the extension’s popup.
3. The first time, read and accept the licence agreement. The application then starts in a new tab.

See using the extension for the first time for a walkthrough of the tab and its side panel.

For organisations

With an Enterprise licence, desktop administrators deploy the extension to managed Chrome and Edge through Group Policy or Intune, and set the licence by policy, where it activates offline. A self-hosted version serves networks that can’t reach the stores, including air-gapped ones. See configure the extension for enterprises and private hosting.

Licensing

Free for personal use and technical evaluation. Business use needs a Desktop licence, bought online for up to 20 desktops. Larger deployments use Enterprise licences, which need no licence server. See licensing.

Privacy

The applications, their files and their traffic stay between your browser and their servers, and don’t pass through us. The extension does send us some information:

• Usage and error statistics when an application starts, to Plausible Analytics, which we host ourselves. They never include the address of the .jnlp file, the application’s name or what you type.
• Bug reports, only if you choose to send one when an application fails to start. A report includes the .jnlp file, which can name your organisation’s internal servers.
• Licence checks, if you activate a licence.

The details are in the privacy policy.

Help and bug reports

When an application fails to start, the extension offers to send us a report. You can also use Report a Bug in the extension’s popup, or open an issue on GitHub. Issues are public: for an internal or private application, write to jnlprunner@leaningtech.com instead. To collect logs for a report, see how to debug the extension.

Questions are welcome on Discord.