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National Grid ESO vs PM2.5 Open Data Portal

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

APINational Grid ESOHEALTHY92PM2.5 Open Data PortalHEALTHY91
Uptime · 30d
Uptime · 90d100%100%
Uptime · 30d100%100%
P50 · ms609796
P95 · ms13111352
Authnonenone
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseNESO Open Data Licence (OGL-based); varies per datasetUnverified
Free tierFree — limits not publishedFree — no API key
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

National Grid ESO vs PM2.5 Open Data Portal: common questions

Which is more reliable, National Grid ESO or PM2.5 Open Data Portal?

Both are neck-and-neck — National Grid ESO and PM2.5 Open Data Portal 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, National Grid ESO or PM2.5 Open Data Portal?

National Grid ESO has the lower median latency in our checks — National Grid ESO responds in 609 ms versus PM2.5 Open Data Portal at 796 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 National Grid ESO and PM2.5 Open Data Portal need an API key?

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

Can I call National Grid ESO and PM2.5 Open Data Portal from the browser?

Only National Grid ESO 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 National Grid ESO and PM2.5 Open Data Portal free for commercial use?

National Grid ESO has unclear commercial terms, and PM2.5 Open Data Portal has unclear commercial terms. 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.