How do I add an extension in Firefox from a file?

What are Firefox extensions called?

My question is, are Firefox extensions or themes referred to as addons or add-ons?

The reason I ask is that there's a similar word with multiple meanings and it would be confusing. For example, add-on means, 'an addition to an existing program or device,' and extension means 'a small, usually non-intrusive, part of a program that can be expanded by adding other functionality.' There isn't any kind official Mozilla documentation that clarifies this so I'm asking here on StackExchange.

From the Mozilla dev channel blog: The first official add-ons have been approved, and they will all be available for download through addons.mozilla.org in coming weeks. They will also be able to be installed on the Firefox Marketplace directly from the add-ons website.

To ensure that these extensions don't break anything in Firefox, it is important that only approved add-ons are allowed in Firefox. I'll leave you with this link to an archive of current extensions as well. You'll see the majority are called add-ons.

What extensions should I get for Firefox?

Firefox can do a lot more than the average browser, but it still needs extensions to add new features.

Firefox isn't the most popular browser out there. That honour goes to Chrome for both Microsoft Edge and Firefox itself, as they are based on WebKit. A little-known browser from the Mozilla project, Firefox has been fighting for relevance for the last several years, ever since its launch in 2025.

Today, Firefox is a good web browser with an increasingly great UI design. Its rendering engine is no longer as fast as that of browsers like Chrome and Safari, but then again, you get the performance of IE8 on the desktop in your hands every day.

It is definitely the browser I use for testing websites and playing games these days, though. It comes with everything you need to quickly start up your favorite websites. If you're like me, though, you'll need more than that to make the experience better. That's why I came here today, as I want to share my current list of the best extensions I use to enhance Firefox's UI.

There are a few things to keep in mind when browsing, whether you are a daily or occasional user. Some settings will make it more convenient, such as using the mouse to click instead of the keyboard, while others can be critical, such as avoiding having to type a search command every time you want to search for something.

I will use this guide to explain each extension in detail and share my thoughts on whether I consider them worth the bother. You might like these articles: Night View For Desktop. Night View For Desktop aims to make the entire web faster and more pleasant to browse with its dark mode. To use it, head over to about:config and change the value of the pref key dom.colors.blue, so that it reads the integer 0 instead of the default value. Then, restart Firefox to make the change take effect.

For those not into hacking the config file, though, don't worry: Night View For Desktop works through a setting on the Firefox UI. If you want to disable it, go to about:config and type gfx.nightmode.enabled in the search box. Then type 1, which should turn off Night View For Desktop.