Frequently Asked Questions

Using Add-ons

What is an add-on?
Add-ons are small pieces of software that add new features or functionality to your installation of Firefox. Add-ons can augment Firefox with new features, foreign language dictionaries, or change its visual appearance. Through add-ons, you can customise Firefox to meet your needs and tastes. Learn more about customisation
Will add-ons work with my web browser or application?
Add-ons listed in this gallery only work with Mozilla-based applications, such as Firefox, Firefox Mobile, SeaMonkey, and Thunderbird. However, not all add-ons work with each of those applications or every version of those applications. Each add-on specifies which applications and versions it works with, such as Firefox 2.0 - 3.6.*. For Firefox add-ons, the install buttons will indicate whether the add-on is compatible or not.
What are the different types of add-ons?
There are several kinds of add-ons that customise Firefox in different ways:
  • Extensions add new features to Firefox or modify existing functionality. There are extensions that allow you to block advertisements, download videos from websites, integrate more closely with social web sites, and add features you see in other applications.
  • Complete Themes change the entire appearance of Firefox, usually including icons, colours, dialogues, and other visual styles.
  • Themes are lightweight themes that use background images to customise your Firefox toolbars.
  • Search Providers add additional choices to the search box dropdown. These providers allow you to quickly search any web site.
  • Dictionaries & Language Packs add support for additional languages to Firefox.
  • Plugins help Firefox display or understand different types of media, such as Adobe Flash or Apple Quicktime.
How do I install, manage, or remove an add-on?
In most cases, add-ons can be installed by simply clicking the install button provided. Add-ons can be managed, disabled, or uninstalled from the Add-ons Manager in Firefox. For more detailed instructions, read this article on extensions or this one for Themes and Complete Themes. If you have difficulty installing add-ons, see Troubleshooting Extensions and Themes.
How do I install add-ons without restarting Firefox?
In Firefox, add-ons marked with "No restart required" can be installed without restarting. These add-ons have been created using the Add-on SDK or bootstrapping. Other add-ons will still require a restart before you can use them.
How do I keep add-ons up-to-date?
Add-ons, unlike plugins, are automatically checked for updates once every day. In Firefox, updates are automatically installed by default. Versions of Firefox prior to 4 (and other applications) will alert you that updates to your add-ons are available. Plugins are not currently automatically checked for updates, so be sure to regularly visit the Plugin Check page to stay up-to-date.
Are add-ons safe to install?
Unless clearly marked otherwise, add-ons available from this gallery have been checked and approved by Mozilla's team of editors and are safe to install. We recommend that you only install approved add-ons. If you wish to install unapproved add-ons or add-ons from third-party web sites, use caution as these add-ons may harm your computer or violate your privacy. Learn more about our approval process
Can add-ons make Firefox slower?
Most add-ons do not cause a perceivable performance decrease in Firefox, though installing an excessive number may have adverse effects. If you suspect an add-on is causing Firefox to be slow, try disabling it.
Firefox told me an add-on isn't compatible. Is there a way I can still use it?
If an add-on isn't compatible with your version of Firefox, it is usually either because your version of Firefox is outdated or the add-on author has not yet updated the add-on to be compatible with a newer version you are using. Mozilla does not recommend trying to circumvent these compatibility checks, as they can lead to browser instability or in some cases loss of data. For users who are testing out alpha or beta versions of Firefox, we offer the Add-on Compatibility Reporter to help add-on developers update their compatibility.
What if I have problems with an add-on?
Add-ons are usually created by third-party developers from around the world, so the best way to get help with an add-on is to look for support links on the add-on's homepage or contact the developer. If you are having issues with Firefox that you suspect are related to add-ons you have installed, visit this support article for troubleshooting tips.
How do I choose between add-ons that seem to do the same thing?
There are often several add-ons that have similar features. To figure out which is right for you, read the entire description of the add-on and view its screenshots. If there are still several in the running, read through the add-on's ratings, user reviews, and statistics to see which is most liked by other users. Remember that you can also just try out both and see which you like better.
What if I can't find an add-on I'm looking for?
With thousands of add-ons available, there's something for everyone. But if you're looking for a particular add-on and can't find it, you might try searching on other sites or posting about it in our Add-ons forum.
What does it mean if an add-on is "experimental"?
Experimental add-ons have been marked by their developers as not suitable for a wide audience. They have been checked by our editors to make sure they don't have security problems, but they may still have bugs or not work properly. Use caution when installing experimental add-ons and uninstall the add-on immediately if you notice problems. Learn more about our review process
What does it mean if an add-on is "not reviewed"?
While all add-ons publicly available in our gallery are reviewed by an editor, you may receive a direct link to an add-on that hasn't yet been reviewed. Use caution when installing these add-ons, as they could harm your computer or violate your privacy. We recommend that you only install reviewed add-ons. Learn more about our review process
How much do add-ons cost to purchase?
Add-ons hosted in our gallery are free unless clearly marked otherwise.
What does it mean when an add-on asks for donations?
Some add-on authors request users who enjoy an add-on to contribute to its development by making a monetary contribution. These contributions go directly to the developer unless a third party is indicated, such as the non-profit Mozilla Foundation.
What are beta add-ons?

Beta add-ons are unreviewed versions which represent the latest work of an add-on author. While different authors have different standards for beta code quality, you should assume that these add-ons are less stable than the general add-on releases.

Please note that when you install an add-on from the "Beta Version" section of an add-on's listing, you will continue to receive updates for that add-on as they become available. Like the initial version you installed, all beta releases are unreviewed by Mozilla and may harm your computer.

What does it mean when an add-on is flagged as slow?
Most add-ons load code and resources at the same time Firefox is starting up. In most cases the impact in start-up time is minimal, but some add-ons can cause a noticeable slowdown.
How do I report an inappropriate or spam user review?
To report a user review of an add-on, log in with your account and visit the add-on's reviews page. Find the review you wish to report, click "Report this review" and select a reason. Our editorial team will investigate the review and take appropriate action.
How do I report a bug or contact the Mozilla Add-ons team?
Please visit our Contact page.
What is a Source Code Licence?

The source code used to create an add-on is an exclusive copyright of the add-on author, unless otherwise declared in a source code licence. Many add-ons on this site have open source licences that make the source code publicly available for copy and reuse under conditions determined by the author. Most authors choose widely known open source licences like the GPL or BSD licences instead of making up their own.

Firefox and other Mozilla software are open source.

Collections and Favourites

What is a collection?
Collections are groups of related add-ons created by users to share.
What is the My Favourites collection?
Favourite add-ons are add-ons that you have bookmarked to easily get back to later. You can add an add-on to your favourites collection by clicking "Add to favourites" on its details page.

Mobile Add-ons

What are mobile add-ons?
Mobile add-ons work with Firefox for Mobile and add or modify functionality just like desktop add-ons. You can find add-ons that work with Firefox for Mobile in our gallery.

Developer Topics

Please see our Developer FAQ and Developer Hub for answers to add-on developer-related questions.

Still have questions?

For general Firefox support, visit our support website. For general add-on and web site questions, visit our forum.