Callook.info vs Urban Observatory

Callook.info is a free, keyless lookup service for FCC-licensed US amateur radio callsigns, returning license status, operator class, name, and registered address as either JSON or XML. A live request for a real callsign returns a wildcard Access-Control-Allow-Origin header with no authentication required, confirming it's safe to call directly from browser code.

Urban Observatory, run by Newcastle University, streams one of the UK's largest real-time urban sensor networks, covering air quality, traffic, flooding, and weather, from thousands of fixed and mobile sensors across Newcastle and partner cities. Its v2 API is fully keyless and exposes sensor locations and readings as JSON, CSV, or Shapefile, with bounding-box filtering for GIS tools. It's an academic, publicly funded service with no commercial tiers.