USAspending.gov is the official online source for tracking U.S. federal government spending. This website and information was launched under the Federal Funding Accountability and Transparency Act of 2006 and then was expanded under the Digital Accountability and Transparency Act of 2014.  

It offers a comprehensive, searchable database of federal awards such as grants, contracts, loans, and other types of financial assistance. Users can filter and view data by agency, award type, recipient, location (state, county, city, zipcode, congressional district), budget function or object class, enabling researchers, journalists, nonprofits, and citizens to trace how taxpayer dollars are allocated.  

The site provides both high-level summaries and detailed datasets; it also includes tools and APIs for downloading or analyzing the data.