Challenge.gov is a technical platform and list of challenge and prize competitions, all of which are run by more than 75 agencies across federal government. These include technical, scientific, ideation, and creative competitions where the U.S. government seeks innovative solutions from the public, bringing the best ideas and talent together to solve mission-centric problems.
You will find hundreds of competitions that cover a wide range of interests and require varying levels of skills and abilities in order to participate. You can discover something of interest to you, sorting by type of challenge and by the agency hosting the competition. They are listed in chronological order, from most recent launched to older, closed competitions going back to 2010.