TransUnion is an American consumer credit reporting agency. TransUnion collects and aggregates information on over one billion individual consumers in over thirty countries including “200 million files profiling nearly every credit-active consumer in the United States”. Its customers include over 65,000 businesses. Based in Chicago, Illinois, TransUnion’s 2014 revenue was US$1.3 billion. It is the smallest of the three largest credit agencies, along with Experian and Equifax (known as the “Big Three”).

TransUnion also markets credit reports and other credit and fraud-protection products directly to consumers. Like all credit reporting agencies, the company is required by U.S. law to provide consumers with one free credit report every year.