Browser Add-ons, Flock, Mozilla, Mozilla Add-ons, Mozilla Firefox, Mozilla Firefox for Mobile, Netscape Navigator, Software, URL Fixer

URL Fixer Has Been Acquired

Update: URL Fixer was acquired and is now hosted at

URL Fixer, one of the first add-ons I wrote for Firefox, has been acquired! It is now being managed by the team at

URL Fixer was inspired in 2006 by this Firefox bug report. Since then, it has been a featured add-on on the Mozilla Add-ons Gallery, it was one of the first add-ons to be compatible with Mobile Firefox, and it placed in the Extend Firefox 2 contest. It used to be compatible with both SeaMonkey and Flock (remember Flock?); its functionality was included in Netscape Navigator 9, and it was at one point under consideration to be included in Firefox 3.

URL Fixer has also been the subject of several experiments: it was the source of the statistics I used in my examination of what people type in the address bar, and it was the add-on I used to test the feasibility of selling a freemium browser add-on.

The new team in charge of URL Fixer recently released version 4, which you can install without needing to restart Firefox; I’m looking forward to seeing what other improvements they make and in what direction they take the add-on. Please note: support questions should no longer go to me; please send them to

Mozilla, Mozilla Firefox, Mozilla Firefox for Mobile, Programming, Technology, URL Fixer

What do people type in the address bar?

Update: URL Fixer was acquired and is now hosted at

Earlier this year, I added a feature to URL Fixer (a browser add-on that fixes errors in URLs that you type in the address bar) that collects anonymous usage stats from users who opt in in order to help improve the ways that URL Fixer corrects typos; the collected data includes domains that are typed in the URL bar as well as the locale (language/country) of the user who typed them.

I now have six months of data, and I’ve run some statistical analysis on it in order to share some interesting stats with you. (If I were more creative, I would make an infographic out of this information.) Note that this data does not include bookmarked links or links that users click on in websites. It is strictly domains that have been typed directly into the address bar.

Care to guess the most commonly typed domain? That’s right: It was typed almost three times as often as the second most popular domain,

The top 10 domains account for 20% of all typed domains. 9% 1.1% 0.5% 3.3% 0.6% 0.5% 3.3% 0.6% 1.1% 0.6%

The most popular TLD for typed domains is .com, followed by .org, .net, and .de.

.com 63%
.org 4%
.net 4%
.de 4%
.ru 2%
.hu 1%
.fr 1% 1%
.br 1%


The top 17 TLD typos are all variations of .com. In order of frequency, they are .com\, .ocm, .con, .cmo, .copm, .xom, “.com,”, .vom, .comn, .com’, “.co,”, .comj, .coim, .cpm, .colm, .conm, and .coom.

The website that appears to benefit the most from users mistyping a legitimate URL is (count the o’s). It’s a scammy website set up to make you think that you have been chosen as a “Facebook Winner.” However, it is only typed once for every 7,930 times that someone correctly types ( and are runners-up in this category, albeit with much less scammy sites in place than

49.5% of domains are typed with a leading “www.”.

The most popular domains:, (a Russian social network), and

The only locales where neither Google nor Facebook control the most popular domain are ru-RU (Russia –, fi-FI (Finland –, a gaming website), ko-KR (Korea –, an e-sports website), and zh-CN (China –

How does domain length correlate with typing frequency?

Domain Length vs Frequency Graph

(Facebook is to thank for the spike at 12 characters.)

How about alphabetical order? Has the old trick of choosing a site name early in the alphabet in order to show up above the fold on DMOZ had any lasting effect?

Facebook and Google certainly make their letters stand out, but there doesn’t appear to be a correlation between the first letter of the domain and its popularity.

None of the domains with more than a 0.0005% share are unregistered, indicating that this kind of usage data would not be very useful to a scammer or phisher looking for new domain names.

Browser Add-ons, Mozilla, Mozilla Firefox, Programming, URL Fixer

My experience with developing a freemium browser add-on

Update: URL Fixer was acquired and is now hosted at

I have written twenty-six add-ons for Firefox in the last five years that I have released for free on Mozilla Add-ons. I enjoy writing add-ons, and because I wrote most of them to fulfill my own needs, I had no problem giving that software away.

At last year’s Add-on Con, some of the major discussions centered around add-on marketplaces and non-free browser extensions. Most parties agreed that the current system of asking for donations is not a viable revenue stream for an independent developer and that add-on developers should have a marketplace to sell their software, if they choose to do so.


Since participating in those discussions, I had been quietly considering developing a freemium add-on: an upgraded version of one of my free add-ons that comes with extra features for those willing to pay a few bucks. I was planning on waiting until a proper add-on marketplace materialized (Mozilla is working on one, as are some independent third-parties), but a few weeks ago, I decided to take the plunge on my own. (Worst case, I’d have a premium add-on ready and waiting as soon as a marketplace opened for business.) I eventually settled on freemium-izing URL Fixer.

URL Fixer is an add-on that helps you avoid typos when typing URLs in the browser’s address bar. According to the statistics gathered by Mozilla, it has been downloaded 960,000 times, and is actively used by 70,000 people. I wrote the first version in June of 2006, and it has gotten generally positive reviews, but the one request that has been consistently raised is for the capacity to add custom corrections — URL Fixer will automatically convert “google.con” to “” (because google.con is most definitely an invalid URL), but it won’t fix “” to “” (because “” might be a legitimate website).

I’ve always resisted adding any sort of correction mechanism that won’t work 100% of the time for 100% of the users (what if someone really wanted to visit, but I could justify this kind of feature in a non-free add-on, as the users who want the feature will pay for the add-on, and the users that don’t want it can continue using the free version.


To confirm my assumptions that people would pay for the ability to add their own corrections, I put a poll on the page that is shown after a user installs URL Fixer. (This page contains basic instructions on how the add-on works in order to cut down on confusion for new users.) This poll asked, “Would you pay .99 for a premium version of URL Fixer that allows you to add custom corrections?”

Out of the several thousand people that saw this page, 78 participated in the poll. Out of those 78, 29 said they’d pay for a premium version of URL Fixer. That’s 37%! You can imagine the numbers that started going through my head at this point – 37% of 70,000 current users is 26,000 users; multiply that by .99, and that’s a quick ,000. (Never mind the 1.5% poll participation rate.)


I spent a few days writing the new features, making sure that the premium version (“URL Fixer Plus“) was able to coexist with the free version if both were installed, and writing a barebones add-on marketplace. Last Friday night, I published URL Fixer Plus and the marketplace, linking them from the firstrun page of URL Fixer. I then went to sleep and waited for the money to roll in.


So how did things turn out? Of the 15,121 people that have upgraded or installed URL Fixer since I released URL Fixer Plus, 342 of them have clicked on the “Try URL Fixer Plus” link. Out of those 342, only 8 decided to actually pay the .99. For those of you not keeping track at home, that’s a conversion rate of 0.05%, a far cry from the ~37% that I expected. So, what could have gone wrong? Take your pick from these possibilities:

  • People don’t read firstun pages.
  • Anyone who didn’t participate in the poll was effectively voting “no,” putting the result much more in line with expectations.
  • Even people who did participate in the poll and said yes changed their mind when it came time to actually pay.
  • .99 is too much.
  • People want to buy the add-on, but they don’t want to use PayPal.
  • People don’t trust me enough to buy something from me.
  • People don’t expect to pay for add-ons at all.
  • All of the above.
  • None of the above.

Even though I’d consider this project a failure thus far, I’ll certainly participate in any legitimate add-on marketplaces that crop up. Several of the possible causes of URL Fixer Plus’s failure could be fixed by having a trusted, discoverable marketplace, and that’s something I can’t build on my own. In the meantime, I’ll continue to offer URL Fixer Plus as an upgrade to URL Fixer. The marginal cost of selling any more copies is essentially zero, so I have nothing to lose.


What are your thoughts? Why did I get such a low conversion rate? What could I have done better?

Browser Add-ons, Mozilla, Mozilla Fennec, Mozilla Firefox, URL Fixer

URL Fixer now compatible with Fennec (Mobile Firefox)

Update: URL Fixer was acquired and is now hosted at

Screenshot of URL Fixer being used in Fennec, the mobile Firefox browser

Fennec is the codename for Mozilla’s work-in-progress mobile browser for phones and smaller computing devices, and since it supports extensions just like Firefox, I’ve started adding Fennec compatibility to the extensions I’ve written (when it makes sense).

URL Fixer version 1.5 is fully Fennec-compatible. I think it’s even more useful in Fennec than in Firefox, given the ease with which one can fat-finger a touch-screen or mini-qwerty keyboard versus on a full-size computer keyboard.

(The screenshot above is from Fennec running on Mac OSX, so your visual results may vary depending on your device.)

Extend Firefox, URL Fixer

URL Fixer places in Extend Firefox 2

Update: URL Fixer was acquired and is now hosted at

The Extend Firefox 2 winners were announced today, and while I didn’t win one of the 3 awesome grand prizes, my submission, URL Fixer, rounded out the list of runner-ups (runners-up?).

First place was taken by Minimap Sidebar Extension by Tony Farndon, which intends to make map/traffic management in the browser less painful; I have to admit, it looks very cool. I’ll be installing it as soon as it supports the latest Firefox beta.

Browser Add-ons, Mozilla Firefox, OPML Support, RSS Ticker, ScribeFire, Tech News, URL Fixer

New Mozilla Addons site is was live

Update: URL Fixer was acquired and is now hosted at

After a series of delays, the new Mozilla Addons site (codenamed Remora) went live late last night. Changes to the site include redesigned visual aspects, localization, and an overhauled discussion/comment system, but probably the biggest change you’ll notice is that new extensions do not undergo a mandatory approval process before being available for download.

As extensions are uploaded, they are relegated to the “Sandbox.” This means that while they won’t appear in search results or under their respective categories, the author can still take advantage of Mozilla’s free add-on hosting by pointing users directly to their add-on’s download page. Sandboxed addons can be nominated for general availability by requesting an editor review, but according to Mozilla, this should be reserved for addons that are of use to the general population and enhance the Web browsing experience, and I fully agree. We don’t need the site cluttered with hundreds of “ Forum Toolbar” extensions that are only used by their author.

As far as my extensions go, ScribeFire and URL Fixer have been deemed public-worthy, and I’ve nominated OPML Support. I’ll probably leave the others (Slashdotter, GoogleTabs) in the sandbox, as they’re not really what I consider “general use.”

Update: It looks like the site has been rolled back to its previous state; I can’t determine why, but the Mozilla Webdev blog will probably post an update. You can still check out Remora at the Mozilla Addons Preview site.