World Bank Open Data
data.worldbank.org
Free access to global development data covering hundreds of indicators across economics, health, education, and environment for every country over decades.
Why it is useful
Provides the most complete longitudinal dataset on global development available for free, with clean APIs and downloadable formats. For economists, journalists, and policy researchers, it is an essential benchmark source for country comparisons. The data quality is far above what you find in news articles because it follows consistent methodological standards across time.