A9 was based in Palo Alto, California, with teams in Seattle, Bangalore, Beijing, Dublin, Iași, Munich and Tokyo.

A9, a subsidiary of Amazon.com, was founded in 2003 with an exclusive focus on producing technology for search and advertising.

They moved into the building previously used by the DEC Systems Research Center in Palo Alto, California.

One purpose of A9.com was to leverage algorithms, and the name was chosen as a numeronym to represent that word (i.e. 'A' + 9 other letters).

A9 developed a protocol called OpenSearch that enabled the "plug-in" search source functionality from the A9.com portal.

A9 developed the first service that allowed users of maps and "yellow pages" (a telephone directory) to view buildings at street level.

[13] Clickriver focused primarily on products and services that complemented Amazon's own offerings.

For example, if a customer viewed a television on Amazon, a Clickriver ad might offer installation services in his or her local area.

[22] Announced in 2003, this service allows customers to search through the full text of hundreds of thousands of books.

[23] The visual search group at A9 created mobile applications that recognize objects and allow users to find these products on Amazon.com.