Dictionaries APIs

Language dictionaries and translations

10 APIs in this category · last checked 2 October 2026
10
APIs listed
4
need no API key (40%)
2
CORS enabled (20%)
9
HTTPS (90%)

This directory lists 10 dictionaries APIs. 2 of them require no API key and support CORS, so you can call them directly from browser JavaScript with no backend and no sign-up. Every entry shows whether it needs authentication, serves over HTTPS and allows cross-origin requests, so you can pick one that fits your stack before you read a single doc page.

Showing 10 of 10 APIs

Collins

Collins' REST API returns monolingual, bilingual, and learner dictionary entries with definitions, translations, and audio pronunciation, gated behind a free registered API key.

Auth: apiKey HTTPS CORS: Unknown

Free Dictionary

Returns word definitions, phonetic transcriptions, audio pronunciation links, and example sentences for English words sourced from Wiktionary, free forever with no signup or API key required.

Auth: No HTTPS CORS: Unknown

Chinese Text Project

Exposes the pre-modern Chinese text library behind ctext.org through plugin and JSON endpoints, free for normal use, though bulk downloading is banned and heavy research access needs a subscription.

Auth: No HTTPS CORS: Unknown

Chinese Character Web

Looks up Unihan Database entries for over twenty thousand CJK ideographs, covering Mandarin, Cantonese, Japanese, Korean, and Vietnamese readings, free, GET only, with CORS enabled and no signup.

Auth: No HTTPS CORS: Yes

Merriam-Webster

Returns definitions, etymologies, audio pronunciations, and synonyms from Merriam-Webster's collegiate and learner dictionaries, free for noncommercial use up to one thousand queries a day per key.

Auth: apiKey HTTPS CORS: Unknown

Words

WordsAPI on RapidAPI returns definitions, synonyms, antonyms, pronunciations, and rhymes for more than one hundred fifty thousand English words, authenticated with the RapidAPI X-Mashape-Key header.

Auth: X-Mashape-Key HTTPS CORS: Unknown

Synonyms

The Synonyms.com API from STANDS4 returns synonyms, antonyms, and part of speech data for a word in JSON or XML, free for up to one hundred queries a day with a registered user ID and token.

Auth: apiKey HTTPS CORS: Unknown

Wiktionary

The Wiktionary Action API exposes Wikimedia's multilingual dictionary data for reading and editing, works without login for basic queries, and supports cross origin calls via an origin parameter.

Auth: No HTTPS CORS: Yes

Oxford

Oxford's Dictionaries API returns definitions, pronunciations, examples, and translations across many languages, priced for enterprise use with licenses near five thousand pounds per language a year.

Auth: apiKey HTTPS CORS: Unknown

Wordnik

Wordnik's API returns definitions aggregated from five dictionaries plus synonyms, antonyms, and examples for over eight hundred thousand words, requiring a free account and an API key request.

Auth: apiKey HTTPS CORS: Unknown

Best Dictionary and Translation APIs for Developers

A dictionary API allows developers to fetch word definitions, phonetic pronunciations, etymologies, synonyms, and translations programmatically. These APIs are essential for building vocabulary apps, language learning tools, and content enrichment pipelines.

Free Dictionary and Wiktionary are the easiest places to start: free, open, no signup. Merriam-Webster and Collins give real publisher dictionaries with editorial definitions and audio, but both need a free API key, and Merriam-Webster caps free use at one thousand queries a day. Oxford covers more languages but its licensing suits enterprise budgets, not side projects. For word relationships beyond a bare definition, WordsAPI and Wordnik add synonyms, rhymes, and usage examples.

The pitfall here is licensing: dictionary content is copyrighted, so free tiers are mainly for testing, commercial use usually needs a paid plan, and automated bulk downloading is banned by sites like Chinese Text Project. Pick Free Dictionary or Wiktionary for prototypes, Merriam-Webster or Collins for editorial accuracy, and Oxford only when the budget allows it.

What to check before you pick one

  • Language coverage: For multilingual apps, confirm the API supports all languages your users need with quality definitions.
  • Audio pronunciations: APIs that include audio pronunciation files enhance language learning and accessibility features.
  • Part-of-speech tagging: Grammatical metadata (noun, verb, adjective) enables advanced linguistic analysis and NLP pipelines.

Frequently Asked Questions

What are dictionary APIs?

Dictionary APIs provide programmatic access to word definitions, pronunciations, etymologies, synonyms, antonyms, and translations across multiple languages for use in educational and linguistic applications.

Is there a free English dictionary API?

Yes. The Free Dictionary API and Merriam-Webster API both offer free tiers. The Free Dictionary API requires no key and provides definitions, phonetics, and example sentences.

Can I get word translations through a dictionary API?

Some dictionary APIs like Oxford Dictionaries include bilingual translation endpoints. For broader translation coverage, translation-specific APIs like DeepL or LibreTranslate may be more suitable.

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