I heard about the InvisibleHand Firefox/Chrome extension on the Windows Weekly podcast, and it sounded like something that would be useful for all the online shopping that I do. Its purpose is to notify you when something you’re looking at or searching for can be found even cheaper at another site on the web. As you can see above when I was searching for a copy of Windows 7 Home Premium on Amazon it notified me that it was $6.50 cheaper on It’s very unobtrusive, which is a must for an add-on like this.

It supports 52 different retailers in the United States, 46 in the U.K., and 15 in Germany. What’s nice is that the “View all offers” button doesn’t take you to ad-ridden site, and instead presents you with a simple drop-down list of the other retailers, sorted by price, who match your product.

The add-on obviously makes money through affiliate programs thereby giving the developers a percentage of the purchases that you make. That doesn’t bother me because I think that it’s a no-brainer way to help support the add-on development cycle. From my point of view the downside is the data they collect:

  • The URL of the site that you originally search for your chosen product on.
  • The characteristics of the product that you search for.
  • The URL of any site that you visit that is notified to you by the Add-on.
  • Other anonymous technical and routing information relating to your product search and any visit that you may make to a third party site that you were alerted to by the Add-on. This information may include your IP address, but you will not personally identifiable from this information.

This add-on is awesome and all, but I’m not a huge fan of products that are keeping tabs on my surfing habits. Unfortunately the only option you really get with InvisibleHand is whether you want it to automatically do price lookups for the things you’re Googling for, too. You can’t actually turn it on or off as needed, which for me is a necessity. Personally I’m going to leave the extension installed, but I’ve disabled it in the add-ons management screen so that I can switch it on only when I need it.

Get InvisibleHand for Firefox or Chrome