CandidWith the merger of Guidestar and the Foundation Center, the 2 leading clearinghouses on nonprofits and foundations, Candid is a primary source of information on the not for profit sector and fundraising. The website contains a vast amount of information on both these broad topics.
Check out Candid's "IssueLab" for free research reports on public affairs topics.
https://foundationcenter.issuelab.org/#