EIA Open Data API (APIv2)
EIA's public, fully RESTful open data API covering more than two million energy time series. Datasets are arranged in a discoverable tree - request a parent route such as /v2/electricity and the API returns its child routes, available frequencies, facets, and data columns as metadata; append /data to retrieve values, with facets, column selection, date range, sort, offset, and length all expressed as query parameters. Route families cover electricity (including hourly RTO and balancing-authority operating data), natural gas, petroleum, coal, nuclear outages, densified biomass, CO2 emissions, international energy, the State Energy Data System, state electricity profiles, and the Short-Term, Annual, and International Energy Outlook projections. Responses are JSON by default or XML with out=xml, capped at 5,000 rows per request with an explicit pagination warning returned in the payload. The legacy APIv1 series interface is deprecated but its identifiers remain reachable through the /v2/seriesid/{id} route. Verified live 2026-07-27 - an unauthenticated GET returns HTTP 403 with API_KEY_MISSING and a bogus key returns HTTP 403 with API_KEY_INVALID. Published API version at the time of review is 2.1.12 (March 2026).