How to Enable Java in Firefox (and Why It No Longer Works)

Note (September 2026): This guide originally implied Java can still be enabled in Firefox. Firefox dropped Java plugin (NPAPI) support in 2017 and removed NPAPI entirely in Firefox 85 in January 2021, so the steps below only applied to old versions.

You cannot enable Java in current versions of Firefox. Firefox 52 (March 2017) dropped NPAPI plugins such as Java, and Oracle says no Firefox version since September 2018 supports them. Java desktop and Web Start-style apps still run outside the browser. If a site says “enable Java”, it often means JavaScript, which Firefox turns on by default.

Key Takeaways

• Firefox 52, released in March 2017, removed support for NPAPI plugins except Flash; the Java plugin is an NPAPI plugin.
• According to Oracle, Firefox 52 ESR was the last release to support NPAPI and is no longer supported; the 64-bit Firefox never supported it.
• Firefox 85, released in January 2021, removed NPAPI support completely, so no setting or add-on brings Java applets back.
• Java applications launched outside the browser are unaffected; OpenWebStart and IcedTea-Web are open-source options for JNLP (Web Start) apps.
• Java and JavaScript are different languages. JavaScript is enabled in Firefox by default and is controlled by the javascript.enabled preference.

The world of the internet is a great way to get your work done with ease. You need not worry about the work being delayed as it gets updated in the system on the spot. But have you ever imagined your life without the internet and all such tools and gadgets?

Simple Guide To Enable Java In Firefox Browser

If no, then you should be aware of how to fix all the issues that you face while using such services. There are many sorts of technical problem that are faced by the users, day in and out. One such problem that is faced by users is how to enable Java in the Firefox browser.

There are many ways to deal with such technical problems. You can either call a technician and get the issue resolved or do it on your own. Technicians are available with ease but charge a lot and might be difficult for you to pay them each time. So how do you solve such issues on your own?

For Java in Firefox, the most useful thing to know first is that the answer changed in 2017: Firefox 52, released in March 2017, removed support for NPAPI plugins (Flash excepted), and the Java plugin is an NPAPI plugin. The sections below explain the old method, why it no longer works, and what to do instead.

How to solve your Problem for Java?

Java is a programming language used to build software for many platforms. In browsers, Java once ran small programs called applets through a plugin. According to Oracle’s Java help pages, Firefox no longer offers any version that supports NPAPI, the technology Java applets need, so there is no setting in current Firefox that turns Java on.

The classic steps below come from Oracle’s help page on enabling Java in a web browser, which lists Windows 10, 7, 8, Vista and XP plus macOS. They only apply to old Firefox releases that still loaded plugins (Firefox 51 and earlier, or Firefox 52 ESR).

Oracle describes the symptom as applets that do not run even after Java is installed, and the cause as Java not being enabled in the browser. On a current version of Firefox the real cause is different: the browser cannot run Java applets at all.

Follow the Different Methods to Enable Java in Firefox Browser

1. You need to restart your web browser before you could enable the Java language on your system. So, close all the open browser windows and reopen it. If the problem persisted on an old, plugin-capable Firefox, Oracle’s steps were as follows (current Firefox has no Plugins section for Java).

• Open the Tools option and click on Add-Ons.
• Find Plugins in the Add-ons manager window.
• For Windows click on Java (TM) Platform plugin and for Mac OS Select Java Applet Plug-in.
• You would find an Enable radio button if on the older version of Firefox. It should be checked, if not then do so. For the new versions select the Ask to Activate or Always Activate button.

On those older Firefox versions, this let applets load again. If you wish to disable Java on Firefox, then the steps would be the same. To disable Java there, you changed the same plugin setting back, on Windows or macOS.

2. You should first check if Java is available in your system or not. If this is not available, then you need to download it and install the same. Installing Java does not add anything to current Firefox, because Firefox no longer loads the Java plugin. The Browser Console steps that follow open a developer tool; they cannot enable Java.

• Select the browser console in the web developer submenu. This is found in the Firefox Menu.
• Press Cmd+Shift+J.
• You would see display messages on the window pane along with the toolbar option.
• The command line at the bottom evaluates JavaScript expressions. JavaScript is a different language from Java, and the console has no way to enable a Java plug-in.

Enable All Java Content

There are many things that one should look out for to keep Java running on Firefox. Java applets are not supported in any current Firefox version. Oracle states that Firefox 52 ESR was the last release to support NPAPI, that it is below the security baseline and no longer supported, and that as of September 2018 Firefox no longer offers a version that supports NPAPI. Installing an outdated browser to run Java is therefore a security risk, not a fix.

Oracle also notes that the 64-bit version of Firefox has never supported NPAPI. Restarting Firefox will not activate Java: Firefox 85, released in January 2021, removed NPAPI support completely.

If you wish to install Java on your system, then you may download it from the official website for installation. This would ensure that you have the most updated version and is not affected by malware. Follow the installation instructions for your operating system on the download page.

Then run the command which is a .exe version. This would install Java on your system. Then as and when needed, Java would run on the system and give you complete use of it. Java installed this way runs desktop Java applications outside the browser; it does not enable Java inside Firefox.

Java-The Common Programming language

Java is a widely used programming language for stand-alone applications and tools. Flash was a separate technology from Adobe, not part of Java, and Firefox removed its last plugin support, used by Flash, in Firefox 85.

You might have many applications and software which would not work if Java is not installed on your system. If a desktop program asks for Java, installing Java lets it run; a web page that asks for the Java browser plugin will not work in Firefox.

Java is not limited to desktop computers. Install it only when an application you use actually requires it.

On the web itself, browser-side features are now built with JavaScript and related technologies rather than Java applets.

Installing Java on a computer is still straightforward, and you can enable or disable it as needed. For Firefox, the practical options are covered below: run Java applications outside the browser, or check whether the site really needs JavaScript rather than Java.

• Enable/Disable JavaScript In Google Chrome.

If the browser is unstable rather than misconfigured, troubleshooting Firefox crashes is the place to go.

Can You Still Enable Java in Firefox?

No. Current Firefox cannot run Java applets, and there is no option to enable them. Java applets depended on NPAPI, the plugin architecture that all major browsers supported for over a decade, according to Oracle. Mozilla removed NPAPI support (except for Flash) in Firefox 52 in March 2017, kept it only in the Firefox 52 ESR channel, and removed the remaining NPAPI support in Firefox 85 in January 2021.

Oracle’s own help page for Java and Firefox says that as of September 2018 Firefox no longer offers a version that supports NPAPI, and that Firefox 52 ESR is below the security baseline. Running that old version to reach a Java applet exposes the computer to years of unpatched browser vulnerabilities.

Java Browser Support Timeline

What to Do Instead of Enabling Java in Firefox

1. Check whether the site means JavaScript

Many “enable Java” messages are really about JavaScript. Although Java and JavaScript are similar in name and syntax, the two languages are distinct and differ greatly in design. As of 2025, 98.9% of websites use JavaScript for client-side behavior, according to Wikipedia’s JavaScript article.

Firefox enables JavaScript by default. Mozilla’s support pages describe how to check it if someone switched it off:

1. Type about:config in the address bar and press Enter.
2. Click Accept the Risk and Continue.
3. Search for javascript.enabled.
4. If the value is false, click the Toggle or Reset button so it becomes true.

Mozilla warns that changes in the Configuration Editor can affect stability, security and performance, so change only this one preference. An extension that blocks scripts can also stop pages from working, so check your extensions too.

2. Run Java applications outside the browser

Oracle notes that the end of NPAPI does not affect Java Web Start applications, which do not interact with the browser once launched; it only affects applets. Oracle later dropped Java Web Start from Java SE 11 and later. For JNLP-based applications, the open-source IcedTea-Web project provides an alternative implementation, and Karakun AG released the open-source OpenWebStart, based on IcedTea-Web, for running such apps after Java 11.

3. Ask the site owner for a supported version

If an internal tool, a government portal or a school system still depends on a Java applet, the long-term fix is on the provider’s side. Wikipedia’s Java applet article notes that alternative technologies such as WebAssembly and JavaScript exist for the role applets once played.

Common Mistakes

• Downloading an old 32-bit Firefox or old Java build from an unofficial site to revive applets. Oracle describes Firefox 52 ESR as below the security baseline.
• Looking for a Java add-on in the Firefox Add-ons Manager. Firefox has no plugin support, so no add-on provides the Java plugin.
• Confusing Java with JavaScript. JavaScript has its own setting; see our guide to enabling or disabling JavaScript in Google Chrome for the Chrome equivalent.
• Treating Firefox crashes as a Java problem. A crashing browser needs Firefox crash troubleshooting, not Java.

Related Reading

• How to make your security settings better on Chrome and Mozilla
• Basics of Java programming for beginners
• Lesser-known Mozilla Firefox tricks

Frequently Asked Questions

Does Firefox support Java?

No. Firefox does not run Java applets. Firefox 52 (March 2017) removed NPAPI plugins except Flash, and Firefox 85 (January 2021) removed NPAPI completely. Java programs that run outside the browser still work on the same computer.

Why is there no Java plugin in the Firefox Add-ons Manager?

The Java plugin used NPAPI, which Firefox no longer supports. Oracle states that the 64-bit Firefox never supported NPAPI and that Firefox 52 ESR, the last version that did, is no longer supported.

Does Chrome run Java applets instead?

No. According to Oracle, Chrome 45 and above dropped NPAPI support, so the Java plugin does not work there either. Wikipedia’s Java applet article adds that applets were removed from Java itself in Java 26 in 2026.

How do I enable JavaScript in Firefox?

JavaScript is on by default. If it was disabled, open about:config, accept the warning, search for javascript.enabled and toggle it to true.

How do I run a JNLP or Java Web Start file today?

Java Web Start is not included in Java SE 11 and later. Open-source tools such as OpenWebStart, based on IcedTea-Web, can launch JNLP applications on current Java versions.

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