candid.org [https://candid.org/]-Formerly known as the Foundation Center. Producer of nonprofit directories, databases, seminars, and management handbooks. Library is located in New York City.
GuideStar [www.guidestar.org]-profits reports and links to 990 tax returns for nonprofit organizations. Note: Access to some sections of the website are fee-based.
Independent Sector [https://independentsector.org/]-coalition of nonprofits, foundations and corporate giving programs. Produces reports and nonprofit sector profiles by U.S. state location.
National Center for Charitable Statistics | Urban Institute [https://nccs.urban.org/]-publishes datasets other statistical reports related to nonprofits and charities. Also produces the publication Nonprofit Sector in Brief .
NYCity Map Portal [http://maps.nyc.gov/doitt/nycitymap/]-map which overlays searchable data sets by population characteristics used by the U.S. census, locations of points of interest (POI) that are non-profit organizations (service center/resident services types, cultural institutions, schools, hospitals) .
Pew Charitable Trusts [https://www.pewtrusts.org/en]-website provides links to nonprofit policy and activity. Parent organization of research organization Pew Research Center.
Nonprofit Explorer-ProPublica [https://projects.propublica.org/nonprofits/]-Propublica database project which allows users to search for tax-exempt organizations in the United States and Internationally. Links to IRS Form 990 filings may be available.