Deploying the Nexthink browser extension on Firefox via JSON

This document describes a procedure for the automated deployment of Firefox extensions using a JSON-file-based enterprise policy, which will be supported starting with the 2026.2 release in February 2026.

This page explains how to force-install Firefox extensions on managed Windows and macOS devices using the policies.json configuration file. Firefox Enterprise Policies enable administrators to deploy extensions, enforce settings, and consistently manage the browser experience across various environments.

While the method is cross-platform, file paths and deployment steps vary slightly across different operating systems.​

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Prerequisites

Before deployment, ensure you have the following:

• Your Firefox extension, packaged as a .xpi file.

• A reliable location from which all target machines can access the extension:

  • Local file system path87900

  • Network share (UNC path)

  • HTTPS-hosted download URL

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Creating the policies.json file

The policies.json file must contain configuration entries for both extension installation and optional consent behavior.

Below are sample policy files for both macOS and Windows operating systems. Update file paths as necessary for your environment.

Note that the flag appex-firefox-consent should be set to true if you want to override user consent and force approval of the extension for the EULA (End-User License Agreement). Set it to false if you want your users to explicitly provide consent.​

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Configuration examples for policies.json

Windows example

{
  "policies": {
    "3rdparty": {
      "Extensions": {
        "{1a5fb18a-1b9b-11ec-a3c7-138a3aa5faee}": {
          "appex-firefox-consent": false
        }
      }
    },
    "ExtensionSettings": {
      "<extension_id>": {
        "force_install": true,
        "install_url": "<extension_url>"
      }
    }
  }
}

macOS example

{
  "policies": {
    "3rdparty": {
      "Extensions": {
        "{1a5fb18a-1b9b-11ec-a3c7-138a3aa5faee}": {
          "appex-firefox-consent": false
        }
      }
    },
    "ExtensionSettings": {
      "<extension_id>": {
        "force_install": true,
        "install_url": "<extension_url>"
      }
    }
  }
}

When configuring policies.json, keep the following in mind:

• Use forward slashes and full paths for file URLs, even on Windows.

• Do not use zipped .xpi.zip files; Firefox expects direct .xpi files.

• HTTPS-hosted install URLs are supported (e.g., "install_url": "https://internal.example.com/extensions/my_extension.xpi").

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Deploying the policies.json file

Windows

1. Locate the Firefox installation folder:

   • Standard installation:

     C:\Program Files\Mozilla Firefox\

   • 32-bit on 64-bit systems or alternate installs:

     C:\Program Files (x86)\Mozilla Firefox\

2. Create the distribution folder:

   mkdir "C:\Program Files\Mozilla Firefox\distribution"

3. Copy the policies.json file into the folder (Run as Administrator):

   copy policies.json "C:\Program Files\Mozilla Firefox\distribution\"

4. Restart Firefox. The specified extension will install automatically.

macOS

1. Locate the Firefox application folder:

   /Applications/Firefox.app

2. Create the distribution directory if it does not exist:

   sudo mkdir -p /Applications/Firefox.app/Contents/Resources/distribution/

3. Copy the policies.json file into the directory:

   sudo cp policies.json /Applications/Firefox.app/Contents/Resources/distribution/

In some cases, manually copying the file may be required if the command fails.

1. Restart Firefox. The extension will install automatically and appear locked in the browser.

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Troubleshooting

In case you encounter problems during this process, the following actions may help you resolve them:

• Double-check all file paths. They must be accessible by the logged-in user.

• Ensure the extension is a valid .xpi file. Zipped versions may not install correctly.

• To diagnose errors, open the following page in Firefox:

  about:policies

• For shared deployments, use UNC paths (e.g., file://server/share/extension.xpi) or web-hosted URLs.

• Ensure that both policies.json and the extension files are readable by Firefox.

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RELATED TOPICS

• Installing the Nexthink Browser Extension