Campaign Finance Reports and Data
The duties of the FEC, which is an independent regulatory agency, are to disclose campaign finance information, to enforce the provisions of the law such as the limits and prohibitions on contributions, and to oversee the public funding of Presidential elections.
Run by the Center for Responsive Politics, whose mission is to: "Inform citizens about how money in politics affects their lives, Empower voters and activists by providing unbiased information, Advocate for a transparent and responsive government."