CheerpJ Applet Runner

Name: CheerpJ Applet Runner
Rating: 3.8 (19 reviews)
Author: Leaning Technologies

Run Java applets without installing Java

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The CheerpJ Applet Runner Chrome extension enables users to run legacy Java Applets directly within modern browsers without the need for Java plugins or installations. It converts Java Applets on the fly into WebAssembly and JavaScript, ensuring compatibility and smooth execution. This extension emphasizes user privacy and security by operating entirely client-side without contacting any servers or collecting user data.

Installation is straightforward: add and pin the extension, then activate it on any applet-based website by clicking the extension icon and enabling it. Developed by Leaning Technologies, CheerpJ Applet Runner offers a seamless solution for accessing Java-based web content, especially useful for legacy applications. The tool is free for non-commercial public network use, with licensing options available for businesses and organizations.

Add-on Developer Tools Productivity Programming Utilities

By:

Users:

Rating:

Version:

2025.6 Last updated: 2025-05-30

Creation date:

2021-09-06

Risk:

Permissions:

scripting
activeTab
storage
declarativeNetRequestWithHostAccess

Size:

126.94M

URLs:

Website ,Privacy policy

Full description:

Source:

Edge Add-on Store

Updated:

a day ago

Ranking

# 750 ▲ 89

Other rankings

#275 in Productivity ▼ 11 #79 in present keyword 29 ▼ 9 #167 in network keyword 21 ▼ 1 #194 in company keyword 10 ▼ 5 #196 in license keyword 3 ▲

Other platforms

CheerpJ Applet Runner (v2025.6)

90,000 4.53

(272)

User reviews

CheerpJ Applet Runner is appreciated for enabling old Java applets to run on modern browsers like Edge, serving as an effective alternative to Internet Explorer mode and avoiding local Java installation. However, users frequently report it fails to launch applets consistently, struggles with page hangs, and requires manual activation for each page, which reduces convenience. Additionally, encoding issues and restricted permission settings were noted. Overall, it is a valuable tool with room for improvement in reliability and usability.

Pros

Allows running old Java applets on modern browsers like Edge and Chrome, enabling access to legacy websites.
Provides a solution to run Java applets without requiring Java installation on the host system, utilizing WebAssembly.
Effectively replaces Internet Explorer compatibility mode for some government and older websites, improving stability and usability.
Simple and functional user interface that adds value for users needing Java applet support.

Cons

Recent versions sometimes fail to launch Java applets or hang, requiring page reloads.
Users must manually activate the add-on (click the icon) on every page, which is inconvenient and repetitive.
Issues with encoding support causing garbled content on web pages containing embedded Java applets.
Limited permission options exist but are mostly disabled, restricting usability and personalization.

Recent reviews

This new version doesn't work anymore :(

by fa*****, 2025-03-02

Tried on 4 different old websites that needed Java to run some features and worked like a charm

by Lu*****, 2025-02-28

Doesn't work at all. Acts like it's going to start the applet, but never actually does.

by *****, 2024-04-07

View all user reviews ›

Extension safety

Risk impact

CheerpJ Applet Runner does not require any sensitive permissions.

Risk impact analysis details

Risk likelihood

CheerpJ Applet Runner has earned a fairly good reputation and likely can be trusted.

Risk likelihood analysis details

High This extension was recently updated in the past month. New updates may not be stable or safe.
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