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PM2.5 Open Data Portal vs US Weather

Same instrument, two spec sheets — measured, not claimed.

APIPM2.5 Open Data PortalNEW—US WeatherNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
Authnonenone
CORSnoyes
HTTPSyesyes
Card requirednono
Commercial useunclearyes
Data licenseUnverifiedU.S. Government work / public domain
Free tierFree — no API keyFree (US Government public data)
Rate limitUnpublishedUnpublished (asks for a User-Agent identifying your app)
In directory since2026-07-052026-07-05
operationalpartialdownno data

PM2.5 Open Data Portal vs US Weather: common questions

Which is more reliable, PM2.5 Open Data Portal or US Weather?

On our scheduled checks, US Weather leads on measured uptime — PM2.5 Open Data Portal at —% versus US Weather at —% over 90 days. These are our own probe results, not provider claims; the uptime bars above show the day-by-day record for both.

Do PM2.5 Open Data Portal and US Weather need an API key?

Neither needs a paid key — PM2.5 Open Data Portal is callable with no signup, and US Weather is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call PM2.5 Open Data Portal and US Weather from the browser?

Only US Weather is browser-friendly — it returns CORS headers over HTTPS. PM2.5 Open Data Portal needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are PM2.5 Open Data Portal and US Weather free for commercial use?

PM2.5 Open Data Portal has unclear commercial terms, and US Weather allows commercial use on its free tier. We track service terms and the data license as separate fields — see the Commercial use and Data license rows above, and confirm both before shipping either in a paid product.