Dictionaries · head-to-head
Free Dictionary vs Merriam-Webster
Free Dictionary API is a keyless REST service built and maintained by a solo developer, returning English word definitions, phonetic spellings, audio pronunciation clips, parts of speech, usage examples, and synonyms/antonyms as plain JSON from a single GET request. It now serves more than 10 million requests a month and is funded entirely through voluntary donations rather than any paid tier.
Merriam-Webster's Dictionary API returns JSON definitions, pronunciations, and audio from the publisher's own Collegiate Dictionary and Thesaurus, plus specialized editions covering medical, learner's, Spanish-English, and grade-banded school dictionaries, each requiring a separate free API key. Keys are issued under a strict non-commercial license capped at 1,000 queries/day/key; using the service in a commercial product requires a separately negotiated agreement with Merriam-Webster.
| Free Dictionary | Merriam-Webster | |
|---|---|---|
| Authentication | None | API Key |
| Pricing | free | free |
| Formats | JSON | JSON |
| CORS | yes | yes |
| HTTPS | Yes | Yes |
Free Dictionary needs no API key, while Merriam-Webster requires API Key — pick Free Dictionary to start without signup.