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Datamuse

Datamuse operates a word-finding query engine and lexical search service for developers, educators, and creative-writing applications. The Datamuse API exposes a /words endpoint that finds words matching a rich combination of semantic, phonetic, orthographic, and vocabulary constraints (means-like, sounds-like, spelled-like, synonyms, antonyms, hypernyms, meronyms, triggers, rhymes, homophones, and more) plus a /sug autocomplete endpoint. Free for non-commercial use up to 100,000 requests per day with no API key required; commercial use, custom vocabularies, and higher rate limits are available via a paid commercial agreement. Datamuse also runs OneLook, OneLook Thesaurus, RhymeZone, Rimar.io, and CivicSearch — consumer-facing word search tools built on the same lexical infrastructure.

1 APIs 11 Features
Word FindingLexical SearchNatural LanguageVocabularySynonymsAntonymsRhymesPhoneticsSemantic SearchReverse DictionaryAutocompleteWordplayCreative WritingVocabulary AppsWord GamesLinguisticsOpen Source ProjectsPublic APIs

APIs

Datamuse API

The Datamuse REST API exposes two operations covering word-finding (/words) and autocomplete suggestions (/sug). The /words endpoint accepts a rich combination of constraint par...

Collections

Pricing Plans

Datamuse Plans Pricing

2 plans

PLANS

Rate Limits

Datamuse Rate Limits

0 limits

RATE LIMITS

FinOps

Features

Means Like (ml)

Reverse-dictionary semantic constraint finding words whose meaning matches an input string of any length.

Sounds Like (sl)

Phonetic constraint returning words pronounced similarly to a given input using a text-to-phonemes algorithm.

Spelled Like (sp)

Orthographic constraint with wildcard pattern matching (* for any chars, ? for a single char).

Predefined Relations (rel_*)

Twelve lexical relations including synonyms, antonyms, hypernyms, hyponyms, holonyms, meronyms, triggers, frequent followers/predecessors, rhymes, near-rhymes, homophones, and consonant matches.

Context Ranking

Topics, left-context (lc), and right-context (rc) parameters skew results toward a document theme or surrounding words.

Lexical Metadata (md)

Optional metadata flags add definitions, parts of speech, syllable counts, pronunciations, and corpus frequency to each word.

Pronunciation Formats

Default Arpabet pronunciations or IPA via the ipa flag, drawing on the CMU Pronouncing Dictionary.

Multilingual Vocabularies

Default English (550k terms) and Spanish (500k terms) vocabularies; custom domain vocabularies available on request.

Autocomplete (/sug)

Intelligent prefix suggestions with spelling correction and semantic fallback when exact matches are unavailable.

No API Key Required

Free non-commercial use up to 100,000 requests per day without an account or API token; HTTPS and HTTP both supported.

Query Echo (qe)

Prepends the result list with a record describing the query string, useful for one-shot word-metadata lookups.

Use Cases

Vocabulary Building Apps

Power flashcards, quizzes, and language-learning apps with synonyms, antonyms, and related-word lookups.

Creative Writing Tools

Drive rhyme finders, thesaurus add-ins, and reverse-dictionary lookups for poetry, songwriting, and copywriting.

Word Games and Puzzles

Generate clues, fill patterns with sp wildcards, and validate word lists for crosswords, hangman, and word ladders.

Autocomplete and Type-Ahead

Provide intelligent prefix suggestions with spelling correction in search bars and form fields.

Educational Software

Add definitions, syllable counts, and pronunciations to reading apps, ESL tools, and accessibility software.

Search Query Expansion

Expand a user's search terms with semantically related words to improve recall in document or product search.

NLP Pre-Processing

Look up word relations, frequencies, and pronunciations as features for downstream NLP pipelines.

Brand and Product Naming

Combine sounds-like, means-like, and spelled-like constraints to brainstorm brand, domain, or product names.

Integrations

OneLook

Datamuse's flagship word search engine indexing 10M+ words across 1000+ dictionaries; built on the same backend.

OneLook Thesaurus

Reverse-dictionary and thesaurus product available on web, as a Google Docs add-on, and as an iOS/Mac app.

RhymeZone

Rhyming dictionary and writing tool partnered with Merriam-Webster, available on web and mobile.

Rimar.io

Spanish-language rhyming dictionary and thesaurus powered by Datamuse's Spanish vocabulary.

CivicSearch

Local government meeting search engine covering 700+ jurisdictions across the US and Canada.

WordNet 3.0

Princeton lexical database supplying synonyms, antonyms, hypernyms, hyponyms, holonyms, and meronyms.

CMU Pronouncing Dictionary

Source for Arpabet pronunciations and the basis for phonetic constraints (sl, rel_rhy, rel_hom, rel_cns).

Google Books Ngrams

Corpus underpinning frequency scores and the rel_jja, rel_jjb, rel_bga, rel_bgb statistical relations.

Wiktionary

Source of definitions returned via the md=d metadata flag.

word2vec / Paraphrase Database

Corpus and embedding sources contributing to means-like and trigger relations.

Obsidian Wordy Plugin

Community plugin embedding Datamuse-powered thesaurus and reverse-dictionary directly into Obsidian.

Model Context Protocol Servers

Multiple community MCP servers (lacausecrypto/datamuse-mcp, pipeworx-io/mcp-datamuse, bhayanak/datamuse-mcp-server) expose the API to LLM agents.

Solutions

Free Non-Commercial Tier

Up to 100,000 requests per day with no API key, no signup, suitable for prototypes, hobby projects, research, and non-commercial education.

Commercial Plan

Custom contract for production traffic in customer-facing applications, higher quotas, custom vocabularies, and SLA — pricing on request.

Custom Vocabulary Hosting

Domain-specific term lists (medical, legal, gaming, internal jargon) hosted on Datamuse infrastructure with all standard relations.

Semantic Vocabularies

Datamuse Context

14 classes · 6 properties

JSON-LD

API Governance Rules

Datamuse API Rules

11 rules · 5 errors 6 warnings

SPECTRAL

JSON Structure

Datamuse Suggestion Structure

0 properties

JSON STRUCTURE

Datamuse Word Structure

0 properties

JSON STRUCTURE

Example Payloads

Datamuse Getwords Example

3 fields

EXAMPLE

Resources

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Vocabulary
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Sources

Raw ↑
opencollection: 1.0.0
info:
  name: Datamuse API
  version: 1.1.0
items:
- info:
    name: Words
    type: folder
  items:
  - info:
      name: Find Words Matching Constraints
      type: http
    http:
      method: GET
      url: https://api.datamuse.com/words
      params:
      - name: ml
        value: ringing in the ears
        type: query
        description: Means like — semantic constraint requiring results with meaning related to the input string (reverse-dictionary
          lookup).
      - name: sl
        value: jirraf
        type: query
        description: Sounds like — phonetic constraint requiring results pronounced similarly to the input.
      - name: sp
        value: hipp*
        type: query
        description: Spelled like — orthographic constraint with wildcards (`*` any chars, `?` single char). URL-encode the
          value.
      - name: rel_jja
        value: ''
        type: query
        description: Popular nouns modified by the given adjective, per Google Books Ngrams.
      - name: rel_jjb
        value: ''
        type: query
        description: Popular adjectives modifying the given noun, per Google Books Ngrams.
      - name: rel_syn
        value: ''
        type: query
        description: Synonyms (WordNet).
      - name: rel_trg
        value: ''
        type: query
        description: Triggers — words statistically associated with the query word in the same piece of text.
      - name: rel_ant
        value: ''
        type: query
        description: Antonyms (WordNet).
      - name: rel_spc
        value: ''
        type: query
        description: Direct hypernyms ("kind of").
      - name: rel_gen
        value: ''
        type: query
        description: Direct hyponyms ("more general than").
      - name: rel_com
        value: ''
        type: query
        description: Direct holonyms ("comprises").
      - name: rel_par
        value: ''
        type: query
        description: Direct meronyms ("part of").
      - name: rel_bga
        value: ''
        type: query
        description: Frequent followers — words that frequently appear immediately after the query word.
      - name: rel_bgb
        value: ''
        type: query
        description: Frequent predecessors — words that frequently appear immediately before the query word.
      - name: rel_rhy
        value: ''
        type: query
        description: Perfect rhymes.
      - name: rel_nry
        value: ''
        type: query
        description: Approximate (near) rhymes.
      - name: rel_hom
        value: ''
        type: query
        description: Homophones — words pronounced the same.
      - name: rel_cns
        value: ''
        type: query
        description: Consonant matches — words with the same consonant skeleton.
      - name: v
        value: ''
        type: query
        description: Vocabulary identifier. Default English (`en`, 550k terms) or `es` for Spanish (500k terms). Custom vocabularies
          available on request.
      - name: topics
        value: technology computers
        type: query
        description: Up to five space- or comma-separated topic words that skew results toward the indicated document theme.
      - name: lc
        value: ''
        type: query
        description: Left context — a single word appearing immediately to the left of the target word.
      - name: rc
        value: ''
        type: query
        description: Right context — a single word appearing immediately to the right of the target word.
      - name: max
        value: ''
        type: query
        description: Maximum number of results to return.
      - name: md
        value: dpsrf
        type: query
        description: "Metadata flags — a string composed of single-letter codes requesting lexical\nmetadata for each result:\n\
          \  * `d` — definitions (and `defHeadword` for inflected forms)\n  * `p` — parts of speech (n, v, adj, adv, u)\n\
          \  * `s` — syllable count (`numSyllables`)\n  * `r` — pronunciation (Arpabet; combine with `ipa=1` for IPA)\n  *\
          \ `f` — corpus frequency (per million words, Google Books Ngrams)\n"
      - name: qe
        value: ''
        type: query
        description: Query echo — prepend a result describing the query string from the named parameter, useful for one-shot
          metadata lookups.
      - name: ipa
        value: ''
        type: query
        description: When set to `1` and pronunciation metadata is requested, return IPA-format pronunciations instead of
          Arpabet.
    docs: 'Find words matching any combination of constraints. Constraints may be combined

      freely; results are ranked by relationship strength for semantic constraints,

      otherwise by frequency. Optional metadata flags add definitions, parts of speech,

      syllable counts, pronunciations, and corpus frequency to each result.

      '
- info:
    name: Suggestions
    type: folder
  items:
  - info:
      name: Get Autocomplete Suggestions
      type: http
    http:
      method: GET
      url: https://api.datamuse.com/sug
      params:
      - name: s
        value: rawn
        type: query
        description: Partially-entered search string for which to return suggestions.
      - name: max
        value: ''
        type: query
        description: Maximum number of suggestions to return.
      - name: v
        value: ''
        type: query
        description: Vocabulary identifier. Default English (`en`, 550k terms) or `es` for Spanish (500k terms). Custom vocabularies
          available on request.
    docs: 'Return intelligent autocomplete suggestions for a partially-entered search string.

      Sorted by popularity; the response may include spelling corrections or semantically

      similar terms when an exact prefix match is unavailable.

      '
bundled: true