Forrester is an American market research company that provides advice on existing and potential impact of technology, to its clients and the public. Their 2016 adjusted EBITDA was $29.3 million and their 2015 adjusted EBITDA was $26.5 million. Forrester has five research centers in the US: Cambridge, Massachusetts; New York, New York; San Francisco, California; Washington, D.C.; and Dallas, Texas. It also has four European research centers in Amsterdam, Frankfurt, London, and Paris and four research centers in the APAC region in New Delhi, Singapore, Beijing, and Sydney. The firm has 27 sales locations worldwide. It offers a variety of services including syndicated research on technology as it relates to business, quantitative market research on consumer technology adoption as well as enterprise IT spending, research-based consulting and advisory services, events, workshops, teleconferences, and executive peer-networking programs.

Forrester was founded in July 1983 by George Forrester Colony, now chairman of the board and chief executive officer, in Cambridge, Massachusetts. The company's first report, "The Professional Automation Report," was published in November 1983. In November 1996, Forrester announced its initial public offering of 2,300,000 shares. In February 2000, the company announced its secondary public offering of 626,459 shares. The company acquired Fletcher Research, a British Internet research firm, in November 1999; FORIT GmbH, a German market research and consulting firm, in October 2000 and Giga Information Group, a Cambridge, Massachusetts-based information technology research and consulting company, in February 2003. In July 2008, Forrester announced the acquisition of New York City-based JupiterResearch. Forrester acquired Strategic Oxygen on December 1, 2009, and Springboard Research on May 12, 2011.

In September 2017, Forrester launched their first consumer product, an Apple and Android mobile app that allows consumers to rate companies using a simple system based upon a stoplight. The app uses the three colors; red for a bad rating, yellow for neutral, and green for good. Users can also leave a comment and the business can also reply once a comment has five or more users.

On January 31, 2006, the company announced that on January 26, 2006 its independent registered public accounting firm, BDO Seidman, LLP, informed the company that it had incorrectly accounted for performance-based stock options to purchase 940,500 shares of common stock granted on March 31, 2005.