ALEXA Actionable Analytics for the Web.

Alexa Internet, Inc. is a California-based subsidiary company of which provides commercial web traffic data.

Founded as an independent company in 1996, Alexa was acquired by Amazon in 1999. Its toolbar collects data on browsing behavior and transmits it to the Alexa website, where it is stored and analyzed, forming the basis for the company’s web traffic reporting.

As of 2014, Alexa provides traffic data, global rankings and other information on 30 million websites, and its website is visited by over 8.8 million people monthly.

Alexa ranks sites based primarily on tracking a sample set of internet traffic — users of its toolbar for the Internet Explorer, Firefox and Google Chrome web browsers.

The Alexa Toolbar includes a popup blocker, a search box, links to and the Alexa homepage, and the Alexa ranking of the site that the user is visiting. It also allows the user to rate the site and view links to external, relevant sites.

In early 2005, Alexa stated that there had been 10 million downloads of the toolbar, though the company did not provide statistics about active usage. The Alexa Toolbar for Internet Explorer 7 has previously been flagged as malware by Microsoft Defender.

A third-party-supplied plugin for the Firefox browser served as the only solution after Amazon abandoned its A9 toolbar. On July 16, 2007, Alexa released an official toolbar for Firefox called Sparky. Originally, webpages were only ranked amongst users who had the Alexa Toolbar installed, and could be biased if a specific audience subgroup was reluctant to take part in the rankings.

This caused some controversy over how representative Alexa’s user base was of typical Internet behavior, especially for less-visited sites. In 2007, Michael Arrington provided examples of Alexa rankings known to contradict data from the comScore web analytics service, including ranking YouTube ahead of Google.

On April 16, 2008, many users reported dramatic shifts in their Alexa rankings. Alexa confirmed this later in the day with an announcement that they had released an updated ranking system, claiming that they would now take into account more data sources “beyond Alexa Toolbar users”.

A number of antivirus companies have assessed Alexa’s toolbar. Symantec classifies the toolbar as “trackware”, while McAfee classifies it as adware, a “Potentially Unwanted Program. McAfee Site Advisor rates the Alexa site as “green”, finding “no significant problems” but warning of a “small fraction of downloads … that some people consider adware or other potentially unwanted programs.”