How to Add Addon Manually in Firefox

Addons or add-ons in Firefox have many uses and also add new features to the browser. For example, an add-on called Adblock is able to remove ads on a site in order to speed up loading when browsing.

All browsers certainly have features to add this Addon/Extension/Add-on. Most of it can be enjoyed for free and can be downloaded on the site webstore each browser. If in Firefox, you can find it on the Firefox Add-Ons page.

Installation of an addon can indeed be done easily through the pages that have been provided. However, you can also install the add-on manually. Of course this is more devoted to testing or creating personal add-ons.

Manually Installing Addons in Firefox

Basically addons in Firefox are stored in an archive file (ZIP) just renamed the format to XPI. It’s the same as in Chrome where the format name is changed to CRX.

So before starting the installation step, please prepare the addon file in XPI format first. And if it’s been prepared, please continue to see how below:

  1. Open Firefox.

  2. Click button triple strip which is in the top right corner.

  3. Then click menu Add-ons.

    Click Add-ons Menu

  4. After that in the Extensionclick the gear icon (settings).

    Click Gear Icon

  5. And continue selecting the menu Install Add-ons from File.

    Manually Installing Add-ons in Firefox

  6. Now search for files XPI that has been prepared and click the Open button.

  7. Done, the addon will be installed immediately and can be activated.

As long as the addon file is not problematic, surely it will be installed perfectly. I also recommend using the Developer version of the Firefox browser for more leverage in managing or testing an addon.

Also read: How to Use Tamper Data in Firefox Quantum

Firefox Addon Solution Failed to Install Due to Signature

So there is a feature in Firefox that serves to check the signature of every file in the add-on archive. So if there is only one file difference, Firefox will cancel the installation process.

The solution is to turn off this signature checking feature. And to do so is very easy. Please first type the command below in the address bar.


Then click the button Accept the Risk & Continue.

After that search “xpinstall.signatures.required“set as false. Then search againextensions.langpacks.signatures.required” and also set it to false.

If it’s done, please restart the Firefox browser and then reinstall it. Surely now the addon can be installed properly without any more signature error notifications.

Hopefully useful and good luck