Lingua Robot vs Wordnik

Lingua Robot is a RapidAPI-hosted REST dictionary covering more than 800,000 English lexical entries — words, phrasal verbs, and multiword expressions — with definitions, pronunciations, and morpheme/lemma data returned as JSON, documented on a separate Apiary reference site rather than its own marketing homepage. A live unauthenticated request against its real RapidAPI proxy host returned a reflected `access-control-allow-origin` header plus `access-control-allow-credentials: true`, reconfirming CORS; its free Basic tier covers 2,500 requests/day (then $0.004 each), with paid Pro/Ultra/Mega plans ($10-$99/month) raising the daily ceiling.

Wordnik's REST API returns word definitions aggregated from multiple published dictionaries alongside example sentences, pronunciations, related words, and corpus-derived frequency data, documented through an interactive Swagger UI. Every developer gets a free Basic plan (100 calls/hour, with an explicit nonprofit/research allowance) before paid Hobby, Pro, and Enterprise tiers raise the ceiling up to 45,000 calls/hour -- revenue that funds Wordnik's nonprofit mission to document the English language.