World Bank Open Data
The World Bank publishes development statistics covering economies, populations, health, education, infrastructure, and the environment across the globe. Its flagship collection, the World Development Indicators (WDI), compiles relevant, high-quality, and internationally comparable time series so you can track a country's progress across decades on a like-for-like basis.
Beyond the headline indicators, the portal hosts a Microdata Library of sample survey data and a Data Catalog for bulk downloads. Everything is available programmatically through an API, and the data is released under CC BY 4.0, so you can reuse it in commercial products as long as you credit the World Bank.
Related sources
Eurostat
The statistical office of the European Union, providing official statistics for Europe. Covers the economy, population, environment, agriculture, trade, and more across EU member states, with harmonised figures that let you compare countries on a like-for-like basis.
IMF Data
A gateway to the IMF's global economic data, giving streamlined access to macroeconomic and financial statistics. Includes International Financial Statistics covering balance of payments, interest rates, national accounts, prices, production, trade, and population for more than 200 countries.
OECD Data
Reports, data, and publications on the economic, environmental, and social conditions in hundreds of countries. Includes International Development Statistics covering aid volume, origin, and types, plus the Creditor Reporting System with detailed information on individual aid activities.
Our World in Data
Research and interactive visualisations on global problems, built by aggregating and harmonising data from official sources. Every chart can be downloaded as a ZIP containing a CSV file, JSON metadata, and a README, and the underlying data is available programmatically via an API. Full provenance is documented for every dataset.