How Does Google Find Websites That Sell Links?

For over a year now, Google has been cracking down on websites which sell links. In most cases, these websites were penalized by losing pagerank (PR). And in other more drastic cases, some of these websites had their pages completely dropped from the Google index.

With consequences this severe, two questions come to mind. First, how does Google find websites that sell links? And second, is Google ever wrong?

How Google Finds Paid Links

Google hints at several techniques for finding paid links, two of which include: (1) information supplied by Google users and (2) a special algorithm.

Method 1: Reliance on the Google Community

Google invites all users to manually report a website that they know is selling or buying paid links. But there is one obvious flaw to this method. Companies or individuals might maliciously use this form to report their competitors. Fortunately, Google does investigate all submissions, but it is hard to imagine that data from the user community would produce many legitimate leads.

Method 2: The Algorithmic Approach

Google also mentions the use of an algorithm which helps find paid links. However, this technique is flawed because paid links are often completely indistinguishable from unpaid links. For example, suppose a tech website such as Engadget were paid to publish a post about a new product from Apple or Dell, and linked directly to the external website. How would this be different from the other articles that they already publish? In fact, unless Google can find a paper trail or other irrefutable evidence that a website is selling links, then most paid links would not be caught.

Does Google Ever Make A Mistake?

So far, there have not been any widespread reports of Google making mistakes by incorrectly penalizing websites. But given that it uses algorithms to find paid links, there is a possibility for error. So here are some tips to ensure that Google never suspects your website.

1. Add nofollow to outbound links

Whenever you link to other websites, you share pagerank (PR). In most cases, this is not a problem. But if it is a paid link, Google does not want you to pass this pagerank on because it manipulates the search results. So all you need to do is to add rel="nofollow" to all such links as shown below.

<a href="" rel="nofollow">Example</a>

Additionally, if you are linking to a commercial website, it is probably a good idea to make links nofollow.

2. Use redirects

Google also suggests the use of redirects, such that all outbound links are redirected via an intermediate page which is blocked from search engines.

What About Websites That Buy Links?

There is very little evidence that Google penalizes websites that buy links. After all, a company could maliciously buy links pointing to its competitor to get the site banned. So for the most part, penalties are directed at the website which sell links.


For more information on paid links, read about Paid Links in Google’s Webmasters/Site owners Help.

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15 Responses to “How Does Google Find Websites That Sell Links?”

  • Yan@Review January 19, 2009 at 8:20 pm

    I’m always against the use of method #1. I figure it’s very much open to abuse by the competitors. How many times I’ve heard of some “authority” sites being stripped of PR due to ‘jealousy’.

    The safest bet is to nofollow all the paid links. I’m using a plugin to nofollow all the links for any category of my choice. You don’t want to anger the God of Google, do you?

    • Velvet Blues January 20, 2009 at 2:00 pm

      Yes, I don’t like the use of info from the community either. But it might be a source of good leads… And anything that makes the web a fairer place makes me happy. But yes, adding nofollow to all paid links is important. What plugin are you using?

  • Ajith Edassery | DollarShower January 20, 2009 at 3:22 am

    Good post… I am all for Google’s approach. I mean, if it’s granting search visibility for certain good content, it’s our responsibility to make sure that we don’t exploit it by selling PR links. That will sabotage the entire algorithm. Since it’s touching its own search preferences and not our sites, nobody has any right to talk against it.

    However, in case Google is making a mistake, I guess they should give the bloggers/site owners another opportunity a few months down the lane. I see this not happening and that’s unethical from Google. And in the case of high profile sites and blogs, Google is in a vengeance mode! :)

    • Velvet Blues January 20, 2009 at 2:00 pm

      I haven’t really heard of any ‘mistakes’. But I feel that Google is fair. And those sites that were slapped with pagerank penalties have been able to recover when they stopped selling paid links. And yes, Google is in vengeance mode. haha. I will never do anything unethical!

  • Kurt Avish January 20, 2009 at 3:44 am

    Having said all that, however Google is extremely happy when we link back with dofollow to any google site :-) Its a bit like an unbalance justice from my point of view.

    I think the best is to set a limit of reasonable amount of links a website can sell… or for example… not more than 1 dofollow link per post of a blog.

    There is a site called Inlinks and I wanted some of you people views about it. It normally gives a plugin to integrate into your site.. But is that not a real easy trap? Google just have to locate this plugin codes and punish the site? Or is it really protected as Inlinks say it?

    • Velvet Blues January 20, 2009 at 11:55 am

      Yes, I am now aware of the linking to Google. It really does help the pagerank of a page.

      As for the ‘Inlinks’ plugin, I haven’t heard of it. I’ll do my research to see what it does.

  • Nihar January 20, 2009 at 9:47 pm

    I always took care about this. But, for me #2. use redirects is new.

    Thanks for the info. Good post.

    • Velvet Blues January 21, 2009 at 2:01 pm

      Yes, sometimes you will notice this with blogs. They never link directly to webpages. The actual url is a redirect through their own website.

  • Kim Woodbridge January 21, 2009 at 5:57 pm

    While google is very helpful in many instances I am a little tired of how much control they have. For example, now they own feedburner – I feel like one company has too much control of our blogging activities.

    I also lost page rank for no apparent reason in November – I’ve never had paid links. Then it “magically” came back in November. It’s seems almost whimsical without any real explanations provided as to what it going on. I think I would like more transparency.

    • Velvet Blues January 22, 2009 at 3:54 am

      Yes, “transparency” is apparently the word of the year. With Google, I agree, they do own too much. And quite often they do things which are not well explained.

      Fortunately, they seem to be a very fair company. But I cannot wait until they get some REAL competition to ‘keep them honest’.

  • Aahna May 20, 2010 at 5:01 am

    hey even i sell links on my site i am getting good money for that, how to stop bcoz in ads i am not getting money but link selling i am getting the money……… :(

  • Rojer Alex August 28, 2010 at 3:45 pm

    There’s no problem in selling / buying links as long as it’s not for manipulating the Google Page Rank algorithm.

    That clearly means that you can buy / sell links for traffic and Google’s absolutely ok with this. This was one of the reasons why the nofollow tag was introduced so that people can still buy / sell links without trying to game the PR algorithm.

  • 3d printer March 17, 2011 at 12:13 pm

    I understand that if you put a link on a site that is nofollow will not pass a vote for pagerank but those it still count as a backlink and a improvement in your serp?

  • Stan September 16, 2012 at 10:47 pm

    Question, I been ranking sites on Google front page, I built one site and it was number 4 for 2 days and now it is on the very last page of google for its given keyword, any idea what type of penalty would cause that?

    • Velvet Blues September 26, 2012 at 11:00 am

      Google search results are always changing. This is often due to new content from other sources or changes in the algorithm. If your site has been penalized, it could be the result of duplicate content, viruses, or black hat SEO techniques.


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