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Blockchair vs Mempool

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

APIBlockchairNEW—MempoolNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
Authnonenone
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified (open-source project)
Free tierFree — limits not publishedFree public API; no key for basic usage
Rate limitUnpublishedEnforced — HTTP 429 on excess, repeated abuse may be banned; numeric limits unpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Blockchair vs Mempool: common questions

Which is more reliable, Blockchair or Mempool?

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

Neither needs a paid key — Blockchair is callable with no signup, and Mempool is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call Blockchair and Mempool from the browser?

Yes — both Blockchair and Mempool 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 Mempool free for commercial use?

Blockchair has unclear commercial terms, and Mempool 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.