AirNow
FreeLiveLast verified 24 Sept 2026
Hourly AQI observations and daily air quality forecasts for the US, Canada and Mexico by zip or coordinate.
Example request
curl -s "https://www.airnowapi.org/aq/observation/zipCode/current/?format=application/json&zipCode=20002&distance=25&API_KEY=$API_KEY"
Free tier, in plain English
Free with a key anyone can request. Each web service has an hourly call cap, and data should be cached since observations refresh hourly and forecasts daily.
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