How many Firefox users use add-ons?

This is a question we’re asked often and have been trying to answer for some time. We’re very excited to say that we now know that answer: at least a third of Firefox users have an add-on installed!

We first tried to tackle this question last year, but the huge amount of data processes led us to call for the help of the Mozilla Metrics Team. Thanks to the help of Simon Krueger, a metrics intern this summer, we now have some insight into the number of add-on users.

On June 22, received 253.7 million add-on update pings, 244.7M of which were for Firefox add-ons. Firefox sends an update ping for each installed add-on once every day it is running, and at other unscheduled times such as installing an incompatible add-on and Firefox upgrades. Not all update pings go to, however — only add-ons hosted there and add-ons that have not set their own URL to check for updates.

Of all of those pings, we counted 32.8M unique IP addresses. This means that the minimum number of active daily users with at least 1 add-on installed was 33.8M, or 33% of Firefox users.

But what about homes and businesses that have multiple computers behind the same IP address? To estimate a number that takes NAT into account, we looked at the number of blocklist pings Firefox sent on the same day, which is how we measure the number of Firefox active daily users. There were 98.6M blocklist pings that day from 61.5M unique IPs. If we apply that ratio to the add-on pings, our estimate jumps to about 52.6M add-on users that day, or 53% of Firefox users.

Usage Chart

For more information on the technical details of this analysis, please read Simon’s post at the Blog of Data.

It’s important to keep in mind that all of the above numbers are active DAILY users. To get the number of monthly Firefox users, we multiply ADU by 3.

A minimum of 33% of users having chosen to install add-ons is great news, and is higher than our previous estimates. It’s especially exciting that we have a new metric to track the success and adoption of add-ons as we launch new features and campaigns encouraging users to customize Firefox and make it their own.

20 comments on “How many Firefox users use add-ons?”

  1. Qurious Orange wrote on

    And how many users wish you just gave them the functionality they wanted in the first place, instead of having to install stupid add-ons?

  2. Ken Saunders wrote on

    Great work on putting this together.

  3. Tony Mechelynck wrote on

    @Qurious Orange: Add-ons are not stupid, they’re part of customizability, which is why I chose Firefox (Fx 0.9, at that time) over IE and even NS several years ago.

    Even the handful of addons that I wouldn’t do without are regarded by some people as “bloat” (not to mention the few tens more that I keep as “additional luxuries”) — and conversely, some people regard as “absolutely essential” some extensions that I would never install. That’s OK: tastes differ. As long as I know where to get the addons I want, I have no problem with that. When talking of addons, I’m “pro-choice” ;-).

  4. DeShock wrote on

    Interesting information.

    @Qurious Orange: The better question is how many users are happy that you didn’t load their browser up with a bunch of crap they don’t want. I know people who are fanatical about certain add-ons they use, but I would NEVER use them. That is the purpose of the add-on system. Let me add what I want and leave off stuff that “for me” just bloats the browser. Some people don’t want any add-ons and appreciate a lean browser. In fact the add-on system is so popular and well recieved that MS has followed the lead of others to make add-ons a part of the IE browser experience.

  5. shamanphenix wrote on

    @Qurious Orange : The choice is a force of the free software. Go install Opera if you don’t want to be free to choice.

  6. malte wrote on

    I suppose that these numbers include add-ons installed by external applications (e.g. Java, Skype, .NET, download managers, Nokia PC Sync, …)? Would it be possible to get a number with the biggest app-installed extensions excluded?

  7. Vin wrote on

    So we must assume that a single ping checks for updates for ALL the addons that a user has installed? If I have 10 addons installed, it wont perform 10 pings right? That would skew the numbers quite a bit.

    Are there any stats on the avg number of addons a user (who falls within the 1/3 ff userbase of having an addon) actually has installed and enabled?

  8. Rangzy wrote on

    I am concerned about the addon-pings. Agree firefox needs it to do the count. But, what all info is sent in the “ping”.

    Its impossible for every firefox user to run wireshark the entire day and dig through the packets to see which addon sends what data in the “ping”.

    Can we have an opt-out option ? Is there one in about:config already ?

  9. Robert Jenkins wrote on

    Thats alot of add-ons. I too am interested in the average number a person has. Right now I have 31 (those are the ones running I have others not compatible with this version of FF) not sure how many are from FF or 3rd parties?

  10. Marcelo wrote on

    Vin, they are counting unique IP pings. If your 10 addons perform 10 pings they will be counted as one.

  11. fearphage wrote on

    It’s really great to finally put some numbers to this. Thanks for the information.

  12. Seth Wagoner wrote on

    Fascinating stuff, cheers for that. I was asked the other day how many Firefox add-on users there were and I explained that it was really hard to answer that question. My guess at the time was 100m, and I’d say I was pretty close because even though half the Firefox ADU use addons, the monthly count would include more of the less sophisticated users who are less likely to use addons, so it’s probably closer to a third.

    I don’t suppose you know how fast the addons userbase is growing, and whether the growth is accelerating, decelerating, or constant?

    And to answer “Qurious Orange”, I’d say there are at least as many people who wish Firefox would stop adding more “features” to Firefox as there are who wish it had the “functionality they wanted”. The problem is, *everyone wants different stuff* and if you put it *all* in, you become bloatware. The only good answer to this problem is to write a decent add-on/plugin architecture, as Mozilla have done.

  13. Wombat wrote on


    “The choice is a force of the free software. Go install Opera if you don’t want to be free to choice.”

    Extensions have got NOTHING to do with free (open source) software. Extensions use an API, and an API can be provided in closed source applications as well.

    Not only that, but you are free to choose with Opera as well. Most popular Firefox extensions can be done in Opera in some way. Opera has many ways to add functionality, including User JS, custom buttons, custom menus, custom toolbars, panels, etc. Someone even wrote a toolbar API for Opera.

    Firefox is great, but I sometimes feel embarrassed as a Firefox user because of some of the fans out there…

  14. Chuck Baker wrote on

    What surprises most is that *only* one third use add-ons. I would have thought this number to be much higher. In fact, I don’t know of a singe Firefox user that does not have at least a few add-ons.

  15. Gingerbread Guy wrote on

    If there’s anyone who works on the add-ons site reading this, please fix these giant annoyances:

    1. Searching for themes yields a list with no previews.

    2. Very often, add-ons show as incompatible with your version of Firefox, e.g. LinkedIn Compainion for Firefox (add-on #1512). Even when you go to the add-on’s details page, there’s no indication of a newer version being available. You have to scroll all the way down to the bottom — and get this — click “View OLDER Versions” to see the newest version! I’ve had a great time explaining that nonsensical bit of information to all the people who complain that the Firefox upgrade broke their add-ons and there’s no update available.

  16. Brent Hopkins wrote on

    One third leaves a lot of room for improvement! I have a suggestion which I think would seriously help with add-on adoption. You see, a lot of Firefox users don’t even know about add-ons at all, or if they have heard about them they don’t really “get it.” I think that if you put a ShareThis (or similar, I just like ShareThis) button on every Add-on page, then you will see greater adoption. Give users an easy way to tweet, Facebook, email it. Also give that option when someone does a review.

    Also, you should expand the Accounts in the Add-ons web site. Make those accounts more social so that I can look at an add-on reviewer’s profile and see what add-ons that person uses and reviews. Let people plug some of their networks into their profile. This will literally increase the “network effect” and will get the word out faster. You could pull way ahead of the pack if you do it right.

    I for one would be very interested to subscribe to the Add-on profiles of a number of people. This would be a great way for me to discover new add-ons.

  17. bluebird wrote on

    I’d like to tell something about an add-on from Firefox. I know I am in the wrong place but I have unsuccessfully tried to register to Firefox to leave my comment. So I’m coming here. The name of the add-on is Weather Channel. I am very angry because it leaves on my computer a malware I cannot take off. The malware is called “Trace.Directory.Desktop Weather!A2”. Its risk level is medium. I have uninstall this add-on for a long time but its crap is still in my machine ! I have tried to contact the Weather Channel site but, strangely, they have no e-mail adress nor a way to write to them. Just a stupid FAQ with stupid answers. Tell everyone what happened to me, to prevent Firefox users for them to don’t download this add-on. Thank you.

  18. brotha wrote on


  19. amin wrote on

    I always receive errors like this:

    Firefox could not install the file at

    because: Download error

  20. Dresandreal Sprinklehorn wrote on

    Qurious Orange says:
    August 11, 2009 at 5:25 pm

    And how many users wish you just gave them the functionality they wanted in the first place, instead of having to install stupid add-ons?

    Well, don’t you think Firefox would move very slowly if at all if all of the current addons abilities were incorporated into Firefox by default.

    I personally love how you can add the ones you want and ignore the others.

    But to each his own. 🙂