Danish data service Energi vs Luchtmeetnet

Energi Data Service is the Danish transmission system operator Energinet's open-data platform, publishing dozens of live datasets — day-ahead power prices, grid emissions, consumption, and more — as a free public JSON API with no key required. Its older Elspotprices dataset was retired after the Nordic market's move to 15-minute settlement on 2025-09-30, superseded by the still-live DayAheadPrices dataset.

Luchtmeetnet is the Dutch national air-quality monitoring network (run by RIVM and partners), publishing measured and forecast pollutant levels from over a hundred stations across the Netherlands. It's a fully open government data feed — no key or registration needed.