A9.com, which went live on April 14, 2004, is an Internet search engine from Amazon.com. Its results derive from Live Search, supplemented by Alexa, Amazon.com and other engines for specific search types.

A9 has many features which many popular search engines lack. In addition to generic web searching, A9 has the ability to search the book results from Amazon.com that include "Search Inside the Book" (as long as a user registers with Amazon.com). Its interface allows users to unite search results together, allowing side by side comparison of results.

A9.com makes use of various search engines for specific uses:

Live Search performs general web and news searching. (From April 14, 2004 to April 30, 2006 Google performed general web and image searching.)

Alexa provides "site info" for general web searches.

Amazon.com offers "Search Inside the Book."

Answers.com looks up reference databases.

Wikipedia (via Answers.com) for encyclopedia entries.

Zoominfo for people summaries.

IceRocket blog search.

The Internet Movie Database offers movie searching.

plus over 400 extra search services that can be added.

The release of A9 was met with some controversy, since it records all of a user's searches and links them to the person's Amazon.com account. A9's privacy statement says:"We may, from time-to-time, employ other companies and individuals to perform functions on our behalf. Examples include sending e-mail and analyzing data. They have access to personal information needed to perform their functions, but may not use it for other purposes."

Some have speculated that A9.com will use data mining for targeted advertising (similar to Gmail). People worried about their privacy can use Generic A9, which does not record personal information.

In January 2005, A9.com added its "BlockView" feature to the Yellow Pages and Maps searches, allowing users to view photos of businesses on many streets in over 24 major U.S. cities after searching for a business name in that city (as of January 2006). Users can also scroll up and down the street view (i.e., up and down the block, hence the name of the feature) in order to see images of other nearby businesses and the areas surrounding them. A9.com planned to continually add new images from a large number of U.S. cities, however the company is no longer offering BlockView to the public.

Service cutback

On September 29, 2006 Amazon discontinued several of the components of A9, including A9 Instant Reward, the A9 Toolbar, A9 Yellow Pages, A9 Maps (including Block View), as well as all other personalization features including the diary, bookmarks, and history.

As a result of the cutback the support for OpenSearch was moved to a community process at OpenSearch.org.