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Datamuse vs Lookup.im API

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

APIDatamuseHEALTHY94Lookup.im APIHEALTHY84
Uptime · 30d
Uptime · 90d92.2%99.02%
Uptime · 30d86.7%100%
P50 · ms1801158
P95 · ms9263581
AuthnoneapiKey
CORSnono
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

Datamuse vs Lookup.im API: common questions

Which is more reliable, Datamuse or Lookup.im API?

On our scheduled checks, Lookup.im API leads on measured uptime — Datamuse at 92.2% 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, Datamuse or Lookup.im API?

Datamuse has the lower median latency in our checks — Datamuse responds in 180 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 Datamuse and Lookup.im API need an API key?

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

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

Neither sends browser-friendly CORS headers reliably, so call Datamuse and Lookup.im API from a server or proxy rather than client-side. The CORS and HTTPS rows above show exactly what we detected for each.

Are Datamuse and Lookup.im API free for commercial use?

Datamuse 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.