GuideStar, the national database of United States charitable organizations, gathers and distributes data on more than 850,000 IRS-recognized nonprofits. A very comprehensive source of information about American nonprofit organizations, GuideStar gathers information about the operations and finances of nonprofit organizations.

This site requires a free registration process to access some of the services. After creating an account, the user will have access to a nonprofit organization's revenues, expenses, balance sheets, and the IRS Form 990.