Dictionaries · head-to-head
Merriam-Webster vs Wiktionary
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.
Wiktionary exposes its full multilingual dictionary — definitions, etymologies, pronunciations, and translations spanning thousands of languages — through the same MediaWiki Action API that powers Wikipedia, with no key required for read access. Cross-origin browser requests need the documented origin=* query parameter rather than a bare Origin header, since that's what actually unlocks the API's CORS headers.
| Merriam-Webster | Wiktionary | |
|---|---|---|
| Authentication | API Key | None |
| Pricing | free | free |
| Formats | JSON | JSON, XML |
| CORS | yes | yes |
| HTTPS | Yes | Yes |
Wiktionary needs no API key, while Merriam-Webster requires API Key — pick Wiktionary to start without signup.