How to open a .xpi file (Windows, Mac, Linux)

Q: Why can't I open my .xpi file?

Usually your computer lacks an app that understands XPI. Install one of the apps listed here, or convert the file to a more common format.

A .xpi file is a Mozilla Cross-Platform Installer (Firefox Add-on). If double-clicking does nothing, your computer simply does not have an app that reads XPI yet. Here is how to fix that on each operating system, using free software wherever possible.

Open a .xpi file step by step

Confirm the file really is a .xpi. Drop it into the WhatFileType file identifier, which reads its signature without uploading anything.
On Windows, open it with Firefox (installs it) or 7-Zip (inspect).
On Mac, use Firefox or The Unarchiver (inspect).
On Linux, try Firefox or unzip (inspect).
Still stuck? Convert the .xpi to zip (rename), which opens more widely.

Best apps to open .xpi files

Windows

Firefox (installs it)
7-Zip (inspect)

macOS

Firefox
The Unarchiver (inspect)

Linux

Firefox
unzip (inspect)

Before you open it: Caution. An .xpi is browser code: a malicious extension can read and alter what you browse. Install only from addons.mozilla.org, where packages are signed and reviewed.

Frequently asked questions

Why can't I open my .xpi file?

Almost always because no installed app understands XPI. Install one of the apps above, or convert the file to a format your existing software already reads.

How do I install an .xpi file in Firefox?

Drag it into a Firefox window or open it via the menu. Firefox verifies Mozilla's signature and asks for the extension's permissions before enabling it.

Why won't Firefox install my .xpi?

Release Firefox refuses unsigned extensions. Get the add-on from addons.mozilla.org, or use Firefox Developer Edition/Nightly if you are testing your own unsigned build.