AidData is an initiative that aims to make aid information more transparent and improve the quality of research on aid allocation and aid effectiveness. AidData offers a searchable database of aid activities around the world with nearly one million entries.
The USD-2009 Deflator queries AidData's GDP deflator database. It lets users take financial data from many countries, currencies and time periods, and convert financial values to a constant currency. The API uses RESTful calls and responses are formatted in XML and JSON.