Lingua Robot vs Synonyms

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.

The Synonyms API is STANDS4 Network's word-lookup service, returning synonym, antonym, and part-of-speech data for a submitted word as either JSON or XML from a single GET request against stands4.com's shared services endpoint — the same backend that powers sibling STANDS4 properties like Rhymes.com and Definitions.net. A live GET and OPTIONS preflight against that endpoint both echoed `access-control-allow-origin: *`; the service is free for up to 100 queries/day, with a paid commercial license available by contacting STANDS4 directly.