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CustomGPT.ai vs Open Library

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

APICustomGPT.aiNEW—Open LibraryHEALTHY—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthapiKeynone
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedMixed — mostly open
Free tierFree tier — API key requiredUnlimited within courtesy limits
Rate limitUnpublishedSoft — identified UA appreciated
In directory since2026-07-052026-05-02
operationalpartialdownno data

CustomGPT.ai vs Open Library: common questions

Which is more reliable, CustomGPT.ai or Open Library?

On our scheduled checks, Open Library leads on measured uptime — CustomGPT.ai at —% versus Open Library 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 CustomGPT.ai and Open Library need an API key?

Open Library needs no key, while CustomGPT.ai requires a free API key. If you want to start calling without signup, reach for Open Library first.

Can I call CustomGPT.ai and Open Library from the browser?

Yes — both CustomGPT.ai and Open Library 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 CustomGPT.ai and Open Library free for commercial use?

CustomGPT.ai has unclear commercial terms, and Open Library 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.