PM2.5 Open Data Portal vs US Weather

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

Uptime · 30d
Uptime · 90d100%100%
Uptime · 30d100%100%
P50 · ms796223
P95 · ms13522086
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?

Both are neck-and-neck — PM2.5 Open Data Portal and US Weather each measure 100% uptime over 90 days on our probe schedule. Reliability here is verified from our own scheduled checks; use the 30-day bars above to see which has been steadier lately.

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

US Weather has the lower median latency in our checks — PM2.5 Open Data Portal responds in 796 ms versus US Weather at 223 ms (P50). Tail latency (P95) is in the table above; for most workloads the median is the number that shapes how the API feels.

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.