Comparison Shopping Engines (CSEs) are also called comparison shopping websites or price comparison websites. Let's take a look at the top comparison shopping engines, which drive most of the product sales and revenue through search engine listings and web ads. Comparison shopping engines list down products based on their price, and also lets the user filter them out based on features, shipping, and other options. CSEs list the products vertically, and hence, belong to the category of vertical search engines. To get listed, a seller must sign-up with them and then submit a desired product feed format. These websites can then automatically source and list data from these feeds into different listings. It was launched as Froogle in 2002, and is now the most popular CSE around, driving maximum clicks and revenue to the e-tailers listed on it. Advertisers not only benefit from the huge traffic that it receives, but also get enrolled in Google AdWords―a PPC advertising program―and their products get more exposure when they show up in the search engine results page (SERP). Official Website: Google Shopping This was founded in 1996, and is considered as one of the top comparison shopping websites. It also features great bidding models such as zero bidding, allowing sellers to sell poor-converting products. Products listed on Shopzilla also receive the benefit of reviews done by Bizrate, and also show up in Google Search results. Official Website: Shopzilla This was launched in 1999, and was the first CSE to include tax and shipping cost information, thus giving a shopper a complete idea about the final price. Alongside price comparisons, it also features coupons and weekly specials. Merchants like PriceGrabber, as they can set the CPC to as low as USD 0.01, and also get the added benefit of being listed on Yahoo Shopping. Official Website: PriceGrabber This is now owned by eBay Inc., but was founded in 1998 as dealtime.com. Dealtime still operates as a related but different website. Shopping.com also partners with TheFind, CNET, etc., to display its products and maximize product exposure for merchants. This results in better sales for merchants and more options for online shoppers. Official Website: Shopping.com Nextag was founded in 1999, as a place where buyers and sellers can negotiate the prices of computer and electronic products. The range of items that Nextag allows merchants to list also includes event tickets and real estate. Official Website: Nextag Amazon Product Ads work on the PPC (pay-per-click) model. After signing up, merchants have to upload the information about their products via FTP, and then allocate the budget to be spent on ads. The ads show up on detail pages, search results, and even in the 'buy box' on Amazon.com, and thus provide more exposure to the items listed by the merchant on their own websites. Official Website: Amazon Product Ads Become was founded in 2004, and includes some highly-desired features in a comparison shopping engine, like price comparison, user and expert reviews, buying guides, etc. Official Website: Become Pronto was launched as a downloadable software in 2005, which ran in the background and let users know about the best deal on a product, by monitoring their activity on a product listing page. It was then moved to pronto.com, a CSE. Later on, it was updated with social features. Users can now buy products by checking user ratings and with the help of product buying guides on pronto.com. Official Website: Pronto.com Yahoo! Shopping is a price comparison engine which works using the Kelkoo Shopping price comparison service that it acquired back in 2004. It obtains its results from a wide range of retailers, meaning that the user is more likely to find the right deal on the item which he/she wishes to purchase. The huge list of vendors generated by Yahoo! Shopping is supplemented with user ratings and reviews listed next to each retailer, which helps the buyer in better identifying a reliable seller. Official Website: Yahoo! Shopping This list of comparison shopping engines will help you save quite a few bucks when you shop online next time. Happy shopping!