Propublica Nonprofit Explorer
"Use this database to view summaries of 3 million tax returns from tax-exempt organizations and see financial details such as their executive compensation and revenue and expenses. You can browse IRS data released since 2013 and access over 9.6 million tax filing documents going back as far as 2001."
Allows a search for either organizations or individuals. Looks across all nonprofit types, not just charities. Right hand column includes links to the data sources Propublica relies on.