From the IMF:
The Global Debt Database (GDD) is the result of a multiyear investigative process that started with the October 2016 Fiscal Monitor. The dataset comprises total gross debt of the (private and public) nonfinancial sector for an unbalanced panel of 190 advanced economies, emerging market economies and low-income countries, dating back to 1950.
About the Database
Working Paper: “Global Debt Database: Methodology and Sources”
52 pages; PDF. Includes all data sources used in developing database.
Global Debt Database Data Files
See Also: Other IMF Data Resources
With global debt currently at a record high, the International Monetary Fund is launching a database of public and private borrowing across 190 countries – virtually the entire world – dating back to the 1950s.