Free Dictionary API vs Lookup.im API

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

Uptime · 30d
Uptime · 90d100%99.02%
Uptime · 30d100%100%
P50 · ms6741158
P95 · ms21963581
AuthnoneapiKey
CORSyesno
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

Free Dictionary API vs Lookup.im API: common questions

Which is more reliable, Free Dictionary API or Lookup.im API?

On our scheduled checks, Free Dictionary API leads on measured uptime — Free Dictionary API at 100% versus Lookup.im API at 99.02% 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 Dictionary API or Lookup.im API?

Free Dictionary API has the lower median latency in our checks — Free Dictionary API responds in 674 ms versus Lookup.im API at 1158 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 Dictionary API and Lookup.im API need an API key?

Free Dictionary API needs no key, while Lookup.im API requires a free API key. If you want to start calling without signup, reach for Free Dictionary API first.

Can I call Free Dictionary API and Lookup.im API from the browser?

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

Are Free Dictionary API and Lookup.im API free for commercial use?

Free Dictionary API has unclear commercial terms, and Lookup.im API 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.