Adblock Plus and (a little) more

Typo correction feature in Adblock Plus · 2012-11-21 16:40 by Wladimir Palant

Update: All the issues noted in the comments have been addressed, the next list update should resolve them. I closed the comments here because I cannot realistically reply to everybody – please use our forum instead.

Lots of Adblock Plus users were complaining about unintentionally landing on web pages that tried to use their mistake by either showing ads to them or even by installing malware. We heard you and thought up a way to fix that. A few months ago we took over the development of the URL Fixer extension and made some substantial improvements. Now this functionality is ready for prime time and has been added to Adblock Plus 2.2.

Enabling typo corrections

This is opt-in functionality, it won’t be enabled by default — it appears that many of our users simply don’t use the address bar any more. However, the first time you mistype something you will be asked whether you want to enable typo corrections. If you click “No” this message will not come up again. Of course you can also just enable (or disable) that feature in the Filter Preferences dialog.

Note that Adblock Plus won’t be able to recognize typos immediately. Unlike URL Fixer it doesn’t come with a database of “correct” domain names, it has to download it first. This should normally happen within 5 minutes after the extension installation or update.

Wrong corrections

Adblock Plus does make occasional mistakes when correcting typos. It can happen that you type in a correct domain name that is very similar to another one which also happens to be more popular. In this situation Adblock Plus might mistakenly correct the address you typed in. Simply click “No” when asked whether the typo was recognized correctly and this domain will be added to your whitelist.

Want to help? URL Fixer extension allows you to send us some data including which corrections you marked as wrong (more information). You have to opt into data collection in the URL Fixer options after installing it. The data we receive from you is fully anonymized and processed by the server automatically in order to create better correction rules.

Note that installing URL Fixer automatically disables the typo correction feature in Adblock Plus.


The typo correction feature is an additional revenue source for the Adblock Plus project. So if you don’t want to support us then you should make extra sure it is disabled. Otherwise this is nothing to worry about.

Whenever typo correction brings you to the site of a large online shop an affiliate ID will be added to the address. This makes sure that if you buy something there we get a small amount of money from the shop. But for you this changes absolutely nothing.


Comment [62]

  1. Alex · 2012-11-24 10:57 · #

    Requirements: Firefox 16 – 20

    <!— firefox —>

    If this extension doesn’t work on FF 10 ESR, please write correct minVersion.

  2. Anonymous · 2012-11-24 18:17 · #

    Visiting “” triggers an infobar incorrectly suggesting instead.

  3. Rob · 2012-11-25 03:39 · #

    Interesting idea – apart from the monetization aspect which makes the ‘protection from malicious web sites’ message seem decidedly too dramatic. That message is misleadingly negative and a bit close to scamming by overstating the exposure and the effectiveness of the solution. My first hit was ‘’, not normally considered a malicious web site, being redirected to The feature is now disabled and I’ll watch with some interest which direction this goes.

    Reply from Wladimir Palant:

    Adblock Plus cannot know every single site that you visit – it merely comes with a database of the common ones and is apparently not too popular with URL Fixer users. As said in the blog post, clicking “No” once is enough and this site will be added to your personal whitelist.

  4. Homer · 2012-11-25 10:36 · #

    I found that abp does corrections like to – which would lead to a very different picture… guess ill be turning this feature off promptly.

    Reply from Wladimir Palant:

    How about just clicking “No” for this correction – and not being bothered again…

  5. Alan · 2012-11-25 20:12 · #

    So that would stop it happening for i[0-46]

    I just had this popup for “”. Suggesting that I actually meant “”, which is a DNS error. (Of course, you won’t let me C+P the text, so I could have typo’d it here :p).

    This wasn’t a manually entered URL which could have been wrong; it was a bookmark. A bookmark accessed using Firefox’s awesomebar, using the keyboard. (“cks”, down arrow, enter). Bugfix please?

    I get the intention, and I don’t know what the algorithm is here, but if you’re discounting then you have a problem!

    Reply from Wladimir Palant:

    Unfortunately, Firefox doesn’t allow distinguishing between bookmarks and things typed in manually. I made sure that is on the list however – and the subdomains.

  6. Alan · 2012-11-25 20:14 · #

    Oh, and I’d already whitelisted that site for adblock plus, so taking that into account might have been nice.

  7. Steve · 2012-11-25 23:05 · #

    It thinks is a typo for, but they’re both actually valid addresses for the same Citi website.

  8. Foxhack · 2012-11-26 01:59 · #

    So apparently “Keenspot”, a huge webcomic host, is the wrong address, and Adblock wants to send me to Teenspot.

    Um, why was this enabled by default?

    Reply from Wladimir Palant:

    It’s not enabled by default, you enabled it. As explained in this post, this feature goes by a list of “correct” domains used by URL Fixer users – and keenspot apparently wasn’t on it until recently.

  9. Foxhack · 2012-11-26 02:11 · #

    Also, please, please, PLEASE put the option to disable this feature in the main plugin options. Don’t leave it in “Filter Preferences”. I thought there was no option to disable this until I looked in there.

  10. Alan · 2012-11-26 11:01 · #

    Thanks for whitelisting That seems to have worked, though not in URL Fixer. Any opinion on the other two bugs I pointed out?

    URL Fixer may not be following the MPL (or being very obscure if they are). Check out and consider the phrase “preferred form of the Covered Code for making modifications”.

    Reply from Wladimir Palant:

    The database is only update every three days.

    Concerning MPL: we already changed the URL Fixer license to GPL 3.0, next release will be using it.

  11. Alan · 2012-11-26 11:45 · #

    The GPL has exactly the same requirement (“preferred form of the work for making modifications to it”).

    Reply from Wladimir Palant:

    Oh, I now understand what you meant. The source code repository ( has an script to update that file – it’s being generated from a list of domain names.

  12. Alan · 2012-11-26 12:38 · #

    Heh, I just found that independently.

    I think that’s still a problem (unless updateRules would be present in the next version of the addon). There’s no way to find the repo from the UrlFixer page(s), is there? Apart from “UrlChecker team” -> “Imprint” in the footer, and then googling your names!

    “GPL3, 6. Conveying Non-Source Forms d) Convey the object code by offering access from a designated place (gratis or for a charge), and offer equivalent access to the Corresponding Source in the same way through the same place at no further charge.”

    A liberal interpretation would allow just linking to the hg web interface (which allows downloading archives of the individual versions), and that would at least fix the main problem.

    A stricter interpretation (of the phrase “the same way”) would be that you need to link directly to full source archives from the UrlFixer page(s). Because the hg web interface is different and complex enough, it’s not obvious to an outsider that you can use it to download e.g.

    Reply from Wladimir Palant:

    Yes, we will make sure that the source code repository can be found – merging two projects isn’t quite easy :)

  13. Anon · 2012-11-26 14:28 · #

    Ah, the shark, she is well and truly jumped. No, I really did want, not the european investment fund!

    Reply from Wladimir Palant:

    See the “false positives” section in the blog post. I’ve made sure is on our list of domains but feel free to click “No” in the typo correction notification to add the domain to your personal whitelist.

  14. Scott · 2012-11-26 15:48 · #

    So what do you have against the Pride of Oklahoma marching band at ? If I wanted to see the bands web site at Boston University, I would have typed “bu” instead of “ou”. (And BU doesn’t have a page at that address anyway.)

    Reply from Wladimir Palant:

    Apparently was on our list of known domains while wasn’t. I’ve made sure that it is always on the list but marking that correction as wrong will make sure you don’t get that message any more.

  15. Jon · 2012-11-26 16:13 · #

    It also seems to suggest (a news site) when people are trying to access our university website
    Can you add it to the list as you did for some other sites above, so I don’t have to get 20 of my friends/colleagues to install the addon and whitelist it that way? ;)

    Reply from Wladimir Palant:

    Done that even though I don’t see that correction myself (probably already gone in the current list).

  16. Merom · 2012-11-26 17:17 · #

    Unfortunately a lock on this new typo correction setting is not yet reflected within the GUI of Adblock Plus. When setting “lockPref(extensions.adblockplus.correctTypos,false)”, the checkbox in the settings dialog is still accessible and even worse actually enables the typo correction setting when clicked (until the next restart of Firefox).

    It would be good if this is fixed in the next version, so that it behaves like the other Firefox settings: If something is locked in the configuration file, then the corresponding checkbox is greyed out in the GUI.

    Reply from Wladimir Palant:

    We never considered locked preferences as a possibility before and it is actually a surprise to me that there is some code out there that does.

  17. Andrew Rossmann · 2012-11-27 00:02 · #

    It’s not clear from the blog post, but will making exceptions in ABP be reflected in future updates, or do you need the separate URL Fixer addin?

    Just as a note, (Tyco Electronics) and (Texas Instruments) need an exception, as they both redirect to other sites (sometimes, sometimes

    Reply from Wladimir Palant:

    No, currently only URL Fixer can send data back to us. Thank you for the report, I’ve added these domains.

  18. Jame · 2012-11-27 05:48 · #

    This really is a horribly implemented extension :-/ eff —> eif any (the parent of wikipedia and other sites) —> wikipedia (which does not have any redirects back to wikipedia), ymail (yahoo, a gmail competitor) —-> gmail, countless universities being redirected to competing universities.

    The amount of false positives that are in this release is so high and so egregious that it should never have been released and you REALLY should consider reverting it even now. You say that it was ready for prime time but sadly it was really very very far from prime time.

    By the way: Do you have a list of known/fixed false positives? You mention a false positive section of the blog post but I have been unable to find it

  19. James · 2012-11-27 06:04 · #

    Also: You mention that this is disabled by default but it very much appears to be enabled by default. It doesn’t ‘redirect’ but it still pops up and confuses people. That very much seems to be enabled to me.

  20. Merom · 2012-11-27 09:59 · #

    @Locked settings:
    Not only some but all the Firefox settings behave that way: You lock a setting and then the corresponding checkbox in the GUI is grayed out. “lockPref(app.update.enabled, false)” will for example disable the GUI controls at Settings > Advanced > Update. Everything else would be usability issue and a reason to file a bug at Mozilla.
    It would be good if the typo correction setting behaved in the same way.

    Reply from Wladimir Palant:

    Yes, that’s because they use the standard preferences widget – and we don’t (and actually cannot without major hacks).

  21. MagerValp · 2012-11-27 10:50 · #

    * (University of Gothenburg, Sweden) is erroneously redirected to * (University of Umeå, Sweden).

    And it’s enabled by default here, I haven’t touched the Adblock Plus settings for ages and it suddenly started popping up in Firefox 17 both at home and at work.

  22. Sewi · 2012-11-27 14:59 · #

    This is not so much feedback, but more a concern.

    Reading other posts seeing that even popular (wikimedia/ymail/texas instruments) and reputable (universities should no doubt be reputable websites) addresses (typed in correctly, mind that), are redirected away to other addresses until they report to you is concerning.

    If I run a website (much less popular than any of the addresses above), am I now required to use AdBlock Plus to catch the chance that visitors are directed away from it en masse, because they use your addon, and the algorithms decide that they must surely have meant a different address?

    I’m not doing anything fishy, but whenever one of my domains I maintain gets popular, I noticed people registering typo-domain names, or identical names with different TLD – sometimes for phishing, sometimes for monetizing visitors that mistyped. The possibility that someone typing in the address correctly may be directed away (for example, as it happened for texas instruments, where the OP meant to go there, but was lead elsewhere) worries me.

  23. Clippy · 2012-11-27 16:08 · #

    Adblock Clippy says: “It looks like you’re trying to access Yahoo Mail in 2012. Would you like me to send you to GMail instead?”

  24. Saphira · 2012-11-27 17:07 · #

    It’s really, really not funny when ABP tries to “correct” something that was already right into something highly NSFW! I went to to check my benefits, and ABP told me “It seems you meant” I’d never seen this message before but thought typo correction would be a handy thing, so I said sure—and landed on a BDSM site (yes, I wondered, yes, I could not have clicked it, but I was a little thrown by the sudden appearance and message, and wasn’t sure how else to turn the feature on).

    For something that’s supposed to protect from malicious sites, well…this thing seems to be calibrated backwards. I’ve turned it off and don’t plan to go anywhere near it again.

    This “feature” is very clearly Not Ready for Prime Time. You guys need to get it together before you roll something like this out.

  25. Indy · 2012-11-27 19:45 · #

    What a horrible, malicious, evil feature. I was wondering why was redirecting to . In fact many of my favorite sites were being redirected to random, seemingly sparse and never updated sites.


  26. Yeah · 2012-11-27 20:30 · #

    AdBlock Plus stay out of my URLs!

    …you had ONE JOB, AdBlock Plus, ONE JOB!

  27. Shark · 2012-11-27 20:54 · #

    Corrects the valid amd safe site who make and sell computer hardware to the distinctly dodgy Sorry bit this feature is dangerous.

  28. paddy · 2012-11-27 21:09 · #

    Tries to correct to, which happens to be a site that could get me into a lot of trouble here at work

  29. David Gerard · 2012-11-27 23:14 · #

    Please stop messing up Wikimedia with this – we have the Wikipedia fundraiser on right now.

  30. Andrew Rossmann · 2012-11-28 00:22 · #

    Found another. (another electronics company) tries to go to, which is dead!

  31. John · 2012-11-28 10:52 · #

    It seems your algorithm is a bit simplistic. If I understand correctly you are redirecting/showing the message, when the URL is similar to another website with a higher importance (according to your URL fixer users). One of your developers stated “we need more data to tweak and improve it” which seems like a very good idea, but not necessarily something you should launch a product with.

    And I agree to the person above stating the message is misleading.

    You really need to think about stepping back from this feature as long as it has this many false positives – which, again, is unfortunately an intrinsic problem of your algorithm.

  32. Johann · 2012-11-28 12:29 · #

    I thought Adblock Plus was about blocking ads. How is this “feature” in any way related to that? Let people download the URL Fixer extension if that’s what they want.

  33. Anonymous · 2012-11-28 12:37 · #

    Major issue with this: whether enabled or disabled, it pops up an infobar every time. If you want to add new optional functionality, fine, but please stop popping up an infobar by default. I install adblock plus on end-user systems as an unobtrusive way to block ads; every time ABP adds more “functionality”, I end up having to find a new way to disable it.

    Reply from Wladimir Palant:

    That notification is a one-time thing asking you whether you want to enable the feature – click “No” and you will never be bothered again.

  34. Geir Aalberg · 2012-11-28 13:37 · #

    It appears that all domains of the pattern * seems to be redirected to the non-existing domain At least that’s what we here at the Norwegian Meteorological Institute have witnessed, which is rather disconcerting when you have 6 million users depending on your weather forecasts. Even when 95 % of ABP users understand how to disable your false positive it still generates a lot of complaints about our services not working.

    Screenshot attached

  35. Arpit Kumar · 2012-11-28 15:27 · #

    >> The typo correction feature is an additional revenue source for the Adblock Plus project.

    Glad to know that this small feature helps you to monetize the ABP.

  36. Andrew Rossmann · 2012-11-28 17:15 · # (STMicroelectronics) needs an exception.

  37. Dan DeNise · 2012-11-28 23:55 · #

    How about a general exception for the domain of the local machine: If my desktop machine is, then never suggest a typo correction against any * URL.

    That won’t help off campus high schoolers looking for, but at least on campus users won’t get scuttled off to

  38. Foo · 2012-11-29 00:08 · #

    At the very, VERY least, this feature needs to be changed so that it ASKS before redirecting. Silently redirecting, and then asking once the new page has been loaded, is a very dangerous idea when your algorithm is so incredibly prone to false positives as this is. There is no way I will turn this feature on while it behaves the way it does.

  39. Anonymous · 2012-11-29 01:47 · #

    > That notification is a one-time thing asking you whether you want to enable the feature – click “No” and you will never be bothered again.

    It seems like every other version of Adblock Plus adds another “one-time thing” to say no to. This generates support issues for people like me who support non-technical end users and want to keep Adblock Plus unobtrusive.

  40. Martin Baranski · 2012-11-29 17:18 · #


    will (and if so, when) this feature be available to Chrome users as well?
    I’m asking, because the latest version doesn’t seem to offer an option to opt-in. :(

    And honestly, I mainly want to active it just to increase my support for you. :)
    Lastly, thanks again for all your hard work.

    Best regards, Martin

  41. Tommi · 2012-11-29 22:22 · #

    Nice idea, but not really working. I’ve gotten three suggestions and they we’re all from a legitimate and correctly spelled out url to some awkward non functional bs site.

    All three cases occured when I only typed a little bit and selected the site url from firefox “awesome bar” as they’re sites I visit on a daily basis. So there’s no chance they even could’ve been wrong.

  42. Captain Rhubarb · 2012-11-30 22:46 · #

    Our web site is “” which is being redirected to either “” or “”

    “AQ” is already really hard to type on a keyboard. I doubt anyone would type our site by mistake!

    Please disable this functionality until your algorithms and overall approach can be improved!

  43. David · 2012-12-01 07:01 · #

    Just a heads up that ABP is asking users who visit (Indianapolis Business Journal) to visit instead. Obviously this is not an error. :)

  44. Daffyd k jones · 2012-12-01 14:19 · #

    ABP needs to be forked, it’s getting too bloated. Every new version comes with a new monetization feature that needs to be disabled – first the “contribute to Adblock” menu item and share on facebook buttons, then the “allow unobtrusive advertising from people who pay Wlad”, and now this typo feature that is completely unrelated to the original purpose of ad-blocking. What next, an e-mail client?

  45. Alexander · 2012-12-01 14:29 · #

    Glad you have made a viable option for us to thank you – I will be using it as soon as it adds some refID at my local store URL

    С уважением,

  46. David · 2012-12-02 02:38 · #

    This feature is absolutely terrible. ABP is supposed to block ads and not to “safe” me from “malicious” websites.
    Please remove this crappy feature.

  47. Karl · 2012-12-02 17:04 · #

    typo correction feature = epic fail

  48. Anonymous · 2012-12-02 17:54 · #

    So attempting to go to brings me instead to a porn site. Yes, that’s an awesome feature you’ve got here, clearly very useful.

  49. Chris Morgan · 2012-12-03 08:17 · #

    Two computers with Adblock Plus installed; two bad suggestions; two computers now with this feature disabled.

    Please, please remove it. Adblock Plus is for removing ads and should only be for removing ads. Single extension, single feature.

  50. Gingerbread Man · 2012-12-03 09:59 · #

    Daffyd k jones wrote:
    “ABP needs to be forked”

    What, again? How many dead forks do users need? The only ones not yet abandoned seem to be Adblock Edge, which is based on recent code and supports pop-up blocking, and Adblock Lite, from the same author, which is based on old code and doesn’t support pop-up blocking.

  51. Alan · 2012-12-03 12:44 · # is still popping up a redirection message on a different computer. I checked for updates, restarted firefox, and it’s the same.

    Version number is 2.2.1.

    I can find no button to update the typo settings (as you say Adblock Plus doesn’t come with them built-in, and fetches them itself). Maybe it’s just having difficulty connecting to the server.

  52. Stephane · 2012-12-03 15:56 · # is redirected to ….

  53. Thomas Arbs · 2012-12-04 12:09 · #

    My first contact with this tool attempted to redirect me from (Ernst&Young, not the smallest of serious corporations) to (Entertainment Weekly, as I first had to learn). Which drew my attention to the worrisome question of forwarding a deep, secure link that might contain sensitive information to a different, insecure site – where it will at least rest in the access logs for the admins to see. Now I am not suggesting Entertainment Weekly’s admins might want to snoop on my tax portfolio, but other cases seem imaginable. Should we really correct deep links that were not typed out? (This one came from a mail.)

  54. Anonymous · 2012-12-04 19:45 · #

    This feature is so annoying and should be an opt-in feature, not opt-out.

    Let people turn it on by themselves.

    It is failure.

    Reply from Wladimir Palant:

    It is an opt-in feature…

  55. gc · 2012-12-05 13:22 · # is corrected to; also, visiting thinks I should go to (which itself redirects to for some paths).

  56. Anonymous · 2012-12-06 01:23 · #

    @Wladmir, in response to your response to comment 54:
    > It is an opt-in feature…

    No, it isn’t. By default, after installation, ABP brings up an infobar every time it thinks the user typoed a domain. That’s not opt-in, that’s intrusive and annoying.

  57. Anonymous · 2012-12-06 01:24 · #

    (My apologies for typoing your name in the previous comment. Ironic, but entirely unintentional.)

  58. Kumi · 2012-12-06 12:24 · #

    Hey man,why don’t you just provide this as an extensive addon just like EBH do?

    Why don’t you guy listen to your users?You still think this feature is good?You mentioned that the feature was disabled by default, so why you bother to WARN people with such an instruction to mislead them enable this feature to avoid malicious sites?

    My words is this feature is crappy.It is still in its experimental status,and not stable enough for daily use.You want say all these misdirect samples are users’ problem? Users don’t help you to improve? Then why you implemented this damned no-one-care feature?

  59. Kumi · 2012-12-06 13:06 · #

    If you can provide an extensive addon of ABP and ask people to try/test then collect samples,it will be a great idea.

    I can’t understand why you implemented an incomplete feature to ABP rather than merge EBH into ABP???

    ABP users were WARNED by the popup bar then choose to enable this feature.Then they found this feature was crappy.Many could do nothing,just had to accept this crappy feature and then turn it off.Some came here to ask,then you told them to turn off.So how you can get data to improve this feature??

    Finally in one sentence: You’ve implemented a useless and meaningless feature to a great extension and wasted plenty of your precious time.

  60. Me · 2012-12-06 21:12 · #

    This is really amazing. It’s time for you to go get a job that pays money, champ. Because “monetizing” ABP is just going to destroy its user base. You already had grumblers about the “unobtrusive ads” feature — mainly that it seems to be an odd feature for an ad blocker, but more seriously that you were giving a free pass to the big boys (ie. Google AdWords) and screwing over the little guys — and now you’ve given what was mostly scattered grumblers a big new platform. This feature is far more sketchy than the whitelist ever was, and far more people are not pleased about it. I get that in this day and age, everything everybody does, especially with computers, has to have some revenue angle — but you could not have picked a worse product to start with these shenanigans on.

    I hope you are watching the install numbers for Adblock Edge, because they are only going to grow. Additionally, I hope you are not paid by your affiliates based on traffic/installed base because not only will you be destroying one of the addons that made Firefox so great, but you’ll end up without much money either.

    Seriously. Step away from the addon. It’s time for you to move on, if this is how you see it. Your users certainly will.

  61. JP · 2012-12-07 04:09 · #

    Can this be removed from the default ADP distribution? It is extremely annoying. If users want this feature, they can install the other extension.

    At least let us disable this crap.

    Reply from Wladimir Palant:

    It’s disabled by default – but you can always disable it in the Filter Preferences of Adblock Plus.

  62. Kumi · 2012-12-07 11:37 · #

    @61 That feature had nothing to do with ADs,but to collect users information.

    All guys don’t want this feature can modify the xpi file by

    Delete files

    Modify these files,delete the line with key word [typo]

    PS: You can ignore the files in locale doesn’t affect anything.

    Reply from Wladimir Palant:

    This feature doesn’t collect any information whatsoever – all checks are executed against a local database of “correct” domains. See our privacy policy, nothing changed there.

Commenting is closed for this article.