Datamuse API

Free word-finding API with no key: rhymes, synonyms, antonyms, related words, spelling suggestions and autocomplete. 100k requests/day. Tested example.

No API key requiredCORS enabledHTTPSFree tier

Endpoint tested and returned HTTP 200 on 2026-08-19

What is the Datamuse API?

Datamuse is a free word-finding API that returns rhymes, synonyms, antonyms, semantically related words, spelling corrections and autocomplete suggestions. It allows 100,000 requests per day with no API key.

Datamuse is the most linguistically sophisticated free API available, and it is barely known outside people building word games. Its query syntax lets you ask remarkably specific questions: words that rhyme with a term, words that sound like it, words that describe it, or words that commonly follow it.

The constraint-combining is where it gets powerful. You can request words meaning something similar to a concept that also start with a given letter and rhyme with another word, in a single query — the kind of search that would otherwise need a full linguistic dataset locally.

Quick facts

Base URL: https://api.datamuse.com
Authentication: No key for up to 100,000 requests per day.
Rate limit: 100,000 requests per day without a key. Higher volumes require contacting the maintainer.
Pricing: Free at this volume, including commercial use.
CORS: Enabled — callable directly from browser JavaScript
Official docs: Read the docs

How to use the Datamuse API

Every request below was executed against the live API on 2026-08-19, and the response shown is the real body it returned — not an illustration.

1. Find words that rhyme with 'forest'

GET https://api.datamuse.com/words?rel_rhy=forest&max=5

curl

curl 'https://api.datamuse.com/words?rel_rhy=forest&max=5'

JavaScript (fetch)

const res = await fetch("https://api.datamuse.com/words?rel_rhy=forest&max=5");
if (!res.ok) throw new Error(`Request failed: ${res.status}`);
const data = await res.json();
console.log(data);

Python (requests)

import requests

res = requests.get("https://api.datamuse.com/words?rel_rhy=forest&max=5", timeout=20)
res.raise_for_status()
print(res.json())

Response — HTTP 200

[
  {
    "word": "florist",
    "score": 9033,
    "numSyllables": 2
  },
  {
    "word": "rainforest",
    "score": 3019,
    "numSyllables": 3
  },
  {
    "word": "reforest",
    "score": 23,
    "numSyllables": 3
  },
  {
    "word": "forrest",
    "score": 15,
    "numSyllables": 2
  },
  {
    "word": "deforrest",
    "score": 3,
    "numSyllables": 3
  }
]

Parameters

Parameter	Type	Required	Description
`rel_rhy`	string	Optional	Words that rhyme with the given word. `forest`
`ml`	string	Optional	Means like — words with a similar meaning. `ocean`
`sl`	string	Optional	Sounds like — phonetically similar words. `elephant`
`sp`	string	Optional	Spelled like, with ? and * wildcards. `t??k`
`rel_trg`	string	Optional	Words statistically associated with the term. `cow`
`max`	integer	Optional	Maximum results, up to 1000. Defaults to 100. `5`

Response fields

[].wordstring: The suggested word.
[].scoreinteger: Relevance score; results are already sorted by it.
[].numSyllablesinteger: Syllable count, when requested via metadata.
[].tagsarray: Part-of-speech and pronunciation tags when metadata is requested.

What you can build with the Datamuse API

Build rhyme and synonym features for songwriting or poetry tools
Power autocomplete and spelling suggestion in a search box
Create crossword and word-game solvers with wildcard spelling queries
Add thesaurus functionality to a writing application

Common errors and how to fix them

Empty array

No words matched the constraints.

Fix: Loosen the query — combining several constraints frequently yields nothing.

Unexpected results

Multiple constraints combine as AND, not OR.

Fix: Each parameter narrows the result set further; use one at a time to debug.

Datamuse API — frequently asked questions

Is the Datamuse API free?

Yes, up to 100,000 requests per day with no API key, and it permits commercial use. Higher volumes require contacting the maintainer.

How do I find rhymes with Datamuse?

Use the `rel_rhy` parameter, for example /words?rel_rhy=forest. Related parameters cover near rhymes, similar-sounding words and much more.

Can I combine several constraints in one query?

Yes, and it is the API's main strength — you can ask for words meaning something similar to one term that also rhyme with another and start with a given letter. Constraints combine as AND, so results narrow quickly.

Does Datamuse support wildcards?

Yes, through the `sp` (spelled like) parameter, where `?` matches one letter and `*` matches any number — ideal for crossword and word-game solvers.

Tools that pair with this API

Word Counter

Count words, characters, sentences, paragraphs and estimated reading time instantly. Free online word counter for essays, blogs and social media.

Text Compare

Compare two texts online free and highlight every difference. A private text comparison tool that finds matches and changes right in your browser.

JSON Formatter

Format, beautify and minify JSON online with 2-space, 4-space or tab indentation. Sort keys alphabetically and catch syntax errors instantly — free and private.

Datamuse is an independent third-party service and is not affiliated with ByteTools or ByteVancer. Details on this page were verified on 2026-08-19; always check the official documentation before relying on this API in production, as terms and limits can change.