Aemet vs RainViewer

AEMET OpenData is the official REST API of Spain's national meteorological agency, publishing forecasts, observations, climatology, and warnings ("avisos") restricted to Spanish territory. Requests return a metadata JSON envelope containing a signed URL that must be fetched separately to retrieve the actual payload (JSON, XML, or CSV depending on endpoint), and the service is documented via an interactive Swagger UI and machine-readable OpenAPI spec.

RainViewer aggregates and re-tiles third-party radar imagery from over 1,200 radar stations across 150+ countries, refreshed every 5 minutes, and exposes it as XYZ PNG tile pyramids plus a JSON timeline endpoint listing available past and short-term nowcast frames. Coverage isn't guaranteed to be permanent since individual source radar owners can request their feed be pulled, and the service is explicitly licensed for personal, educational, and small-scale community projects only.