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Blockchair vs OpenSea

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

APIBlockchairNEW—OpenSeaNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthnoneapiKey
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree — limits not publishedFree tier — API key required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Blockchair vs OpenSea: common questions

Which is more reliable, Blockchair or OpenSea?

On our scheduled checks, OpenSea leads on measured uptime — Blockchair at —% versus OpenSea 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 Blockchair and OpenSea need an API key?

Blockchair needs no key, while OpenSea requires a free API key. If you want to start calling without signup, reach for Blockchair first.

Can I call Blockchair and OpenSea from the browser?

Yes — both Blockchair and OpenSea send CORS headers over HTTPS, so front-end code can fetch either directly with no backend proxy. That makes them easy to swap in a client-side app while you compare responses.

Are Blockchair and OpenSea free for commercial use?

Blockchair has unclear commercial terms, and OpenSea 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.