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Cartes.io vs What3Words

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

APICartes.ioHEALTHY92What3WordsHEALTHY96
Uptime · 30d
Uptime · 90d99.02%100%
Uptime · 30d100%100%
P50 · ms612391
P95 · ms11601181
AuthnoneapiKey
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverified (open-source project; user-generated maps)Unverified
Free tierFree, no API key for public readFree tier — key may be required
Rate limit60 req/window · 59 remainingUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Cartes.io vs What3Words: common questions

Which is more reliable, Cartes.io or What3Words?

On our scheduled checks, What3Words leads on measured uptime — Cartes.io at 99.02% versus What3Words at 100% 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, Cartes.io or What3Words?

What3Words has the lower median latency in our checks — Cartes.io responds in 612 ms versus What3Words at 391 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 Cartes.io and What3Words need an API key?

Cartes.io needs no key, while What3Words requires a free API key. If you want to start calling without signup, reach for Cartes.io first.

Can I call Cartes.io and What3Words from the browser?

Only Cartes.io is browser-friendly — it returns CORS headers over HTTPS. What3Words needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are Cartes.io and What3Words free for commercial use?

Cartes.io has unclear commercial terms, and What3Words 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.