Competitor Information
Many of the databases mentioned here provide a list of competitors, but it's likely imperfect, generated based on NAICS or SIC codes. If you have a suspicion that the competitors are incomplete or incorrect, go with your gut and find other ways to discover them, based on your own familiarity with the industry, and comparing other companies by sales/revenue or market share. You can also find more like-businesses in trade & business news publications, tradeshow exhibitor directories, membership directories, and business to business sites.