1. Executive Summary Java applets and Java browser plugins are no longer supported in any modern Firefox version. Mozilla removed NPAPI (Netscape Plugin Application Programming Interface) support for Java (and most other plugins except Adobe Flash) starting with Firefox 52 (released March 2017). Firefox 52 was an Extended Support Release (ESR) that maintained limited plugin support until Firefox 52 ESR's end-of-life in September 2018. Current Firefox versions (100+) have zero capability to run Java applets via plugins. 2. Historical Context | Firefox Version | Release Date | Java Plugin Status | |----------------|--------------|--------------------| | Firefox 3.6 | 2010 | Full NPAPI support for Java | | Firefox 20–51 | 2013–2017 | NPAPI support, but click-to-play required | | Firefox 52 | March 2017 | Last version with NPAPI (excluding Flash) | | Firefox 52 ESR | Sept 2018 (EOL) | Final version supporting Java plugins | | Firefox 53+ | April 2017+ | No Java plugin support |
// manifest.json for Firefox extension
This allows launching a Java process, not embedding an applet. If you attempt to re-enable Java plugins via old Firefox forks (Waterfox, Pale Moon):
<script src="https://cjrtnc.leaningtech.com/3.0/cj3.js"></script> <script> cheerpjRunJar("/app/myapplet.jar"); </script> Limitations: Limited Swing/AWT support, performance overhead, license cost. Open-source Java Web Start implementation that can launch applets, but requires external window. 6. Firefox Plugin Architecture Evolution | API | Supported Versions | Java Support | Status | |-----|-------------------|--------------|--------| | NPAPI | Firefox 1–52 | Yes (until 52) | Deprecated | | PPAPI (Pepper) | Never in Firefox | No | Chrome/Chromium only | | WebExtensions | Firefox 45+ | No | Current extension API | | Native Messaging | Firefox 50+ | Partial (launch external Java) | Available |
"name": "JavaLauncher", "permissions": ["nativeMessaging"], "applications": "gecko": "id": "java-launcher@example.com"
