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Weather Underground API vs Website Carbon

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

APIWeather Underground APIREACHABLE100Website CarbonHEALTHY100
Uptime · 30d
Uptime · 90d100%100%
Uptime · 30d100%100%
P50 · ms10437
P95 · ms1117166
AuthapiKeynone
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — API key may be required for productionFree keyless byte-based /data endpoint
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Weather Underground API vs Website Carbon: common questions

Which is more reliable, Weather Underground API or Website Carbon?

Both are neck-and-neck — Weather Underground API and Website Carbon 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, Weather Underground API or Website Carbon?

Website Carbon has the lower median latency in our checks — Weather Underground API responds in 104 ms versus Website Carbon at 37 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 Weather Underground API and Website Carbon need an API key?

Website Carbon needs no key, while Weather Underground API requires a free API key. If you want to start calling without signup, reach for Website Carbon first.

Can I call Weather Underground API and Website Carbon from the browser?

Only Weather Underground API is browser-friendly — it returns CORS headers over HTTPS. Website Carbon needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are Weather Underground API and Website Carbon free for commercial use?

Weather Underground API has unclear commercial terms, and Website Carbon 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.