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Free Public APIs API vs Open Library

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

APIFree Public APIs APIHEALTHY88Open LibraryHEALTHY73
Uptime · 30d
Uptime · 90d100%88.2%
Uptime · 30d100%81.7%
P50 · ms8781629
P95 · ms24194878
Authnonenone
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedMixed — mostly open
Free tierFree — limits not publishedUnlimited within courtesy limits
Rate limitUnpublishedSoft — identified UA appreciated
In directory since2026-07-052026-05-02
operationalpartialdownno data

Free Public APIs API vs Open Library: common questions

Which is more reliable, Free Public APIs API or Open Library?

On our scheduled checks, Free Public APIs API leads on measured uptime — Free Public APIs API at 100% versus Open Library at 88.2% over 90 days. These are our own probe results, not provider claims; the uptime bars above show the day-by-day record for both.

Which is faster, Free Public APIs API or Open Library?

Free Public APIs API has the lower median latency in our checks — Free Public APIs API responds in 878 ms versus Open Library at 1629 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 Free Public APIs API and Open Library need an API key?

Neither needs a paid key — Free Public APIs API is callable with no signup, and Open Library is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call Free Public APIs API and Open Library from the browser?

Yes — both Free Public APIs API 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 Free Public APIs API and Open Library free for commercial use?

Free Public APIs API 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.