The Grantsmanship Center
https://www.tgci.com/

This site includes information and links to funding sources, a database with samples of funded proposals for several federal grant programs, and information about training that the Grantsmanship Center offers throughout the country. One of the most valuable services that this site provides is daily Federal Register grant announcements in an easy-to-access format.

Grants.gov
https://www.grants.gov/

This is the main government portal for all grant-related information. It includes daily grant announcements, a searchable grant database, and links to specific federal departments and programs. It's the best single resource for leads on federal funding programs.

GuideStar
https://www.guidestar.org/

GuideStar is a searchable database of more than 1.8 million nonprofit organizations in the United States. Type a name in the Search box to find your favorite charity, or use the Advanced Search option to find an organization by subject, state, ZIP code, or other criteria.

Urban Institute
https://www.urban.org

The Urban Institute provides information by gathering data and performing original research on social and economic issues. Its goal is to foster sound public policy and effective government. Much of the Institute's work has to do with the nonprofit sector. Its publications and resources can be useful when you're writing grants.

Rural Information Center
https://www.nal.usda.gov/ric

Does your organization undertake projects in rural areas? The National Agricultural Library, part of the U.S. Department of Agriculture, offers this page of links related to grants for rural areas. Check out the menus on the left and right sides of the page too. They include links to information about rural education, rural health, rural housing, and sustainable communities.