Words API
Words API is a RESTful English-language API that provides definitions, synonyms, antonyms, related words, syllables, pronunciation (IPA), rhymes, frequency, and hierarchical lexical relationships (typeOf, hasTypes, partOf, hasParts, memberOf, similarTo, also, entails, inCategory, inRegion, pertainsTo, etc.) for more than 150,000 English words. Distributed and metered through the RapidAPI marketplace.
Real signal across most facets with visible, nameable gaps — the contract exists but is thin, or the portal is good while governance and commercial terms are absent.
API Evangelist profiles Words API the way a machine reads it — 154 machine-readable artifacts across 9 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Words API scores 59.5/100 (developing), with a separate agent-readiness read of 48/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-07-27 · rubric v0.5
How we profile Words API
Each block below is one kind of artifact we hold for Words API. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 9
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
Words API Categories API
Words API Category, Region, and Domain-Usage Relationships.
Words API Definitions API
Words API Sense-level Definitions Grouped by Part of Speech.
Words API Examples API
Words API Real-world Example Sentences for Each Sense.
Words API Frequency API
Words API Corpus-derived Frequency Statistics (Zipf, perMillion, diversity).
Words API Hierarchy API
Words API Lexical Hierarchies — typeOf, hasTypes, partOf, hasParts, instances.
Words API Phonetics API
Words API Pronunciation (IPA), Syllables, and Rhymes.
Words API Search API
Words API Search and Random Word Discovery Endpoint.
Words API Thesaurus API
Words API Synonyms, Antonyms, and Similar Word Relationships.
Words API Word API
Words API Lookup a Word and Retrieve Its Full Lexical Entry.
Scroll within the panel for all 9 ·
Open Collections 1
Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
Words API
OPEN COLLECTIONPricing Plans 1
Pricing is part of the interface. Machine-readable plans tell you what a tier costs and includes before you commit — one of the six things the Kin Score reads for commercial clarity.
Published pricing tiers and plan structures.
Words Plans Pricing
PLANSRate Limits 1
Rate limits are the difference between a demo that works and a production integration that doesn't fall over. Publishing them is an operational-transparency signal — and a hard requirement for any agent that plans its own throughput.
Documented rate limits and quota policies.
Words Rate Limits
RATE LIMITSFinOps 1
Cost, billing, and metering signals let a buyer model the financial operations of an API before it's live. We profile them for the same reason we profile pricing: the money is part of the contract.
Cost, billing, and metering signals for API financial operations.
Words Finops
FINOPSFeatures 11
The notable capabilities this provider advertises, captured as structured features so they can be searched and compared instead of read one landing page at a time.
Notable capabilities this provider offers.
150,000+ English Words
Definitions, syllables, pronunciation, and lexical relationships across more than 150,000 English words.
Definitions and Parts of Speech
Per-sense definitions grouped by part of speech (noun, verb, adjective, adverb).
Thesaurus (Synonyms and Antonyms)
Interchangeable and opposite-meaning words for each sense of a word.
Lexical Hierarchies
typeOf, hasTypes, partOf, hasParts, instanceOf, hasInstances, memberOf, hasMembers, substanceOf, hasSubstances, inCategory, hasCategories relationships.
Pronunciation in IPA
International Phonetic Alphabet pronunciation, optionally split per part of speech.
Syllable Breakdown
Syllable count and the ordered list of syllables for each word.
Rhymes
Lists of rhyming words, distinguished by pronunciation variant where pronunciations differ.
Frequency Data
Zipf frequency (1–7), per-million occurrence rate, and corpus diversity score derived from large English subtitle corpora.
Examples
Sample sentences illustrating real usage for each sense.
Regional and Domain Usage
inRegion, regionOf, inCategory, hasCategories, usageOf, hasUsages relationships connect words to dialects and subject domains.
Random and Filtered Word Search
/words search endpoint supports letter count, letter pattern, phoneme count, IPA pattern, part of speech, and random selection.
Scroll within the panel for all 11 ·
Semantic Vocabularies 1
JSON-LD contexts give the data shared meaning across APIs. We profile them because semantics are what let a machine reconcile 'customer' here with 'customer' somewhere else.
JSON-LD contexts and semantic vocabularies used across these APIs.
Words Context
JSON-LDSpectral Rules 2
Governance rulesets we run against this provider's specs — the automated checks behind parts of the score. Profiling them makes the quality bar explicit and re-runnable, not a matter of opinion.
Words API API Rules
SPECTRALWords API API Rules
SPECTRALJSON Schema 36
Standalone JSON Schema definitions describe the data models behind the API. We profile them so the shapes are validatable on their own — useful long after a single request is forgotten.
Standalone JSON Schema definitions for this provider's data models.
AlsoResponse
JSON SCHEMAAntonymsResponse
JSON SCHEMADefinitionEntry
JSON SCHEMADefinitionsResponse
JSON SCHEMAEntailsResponse
JSON SCHEMAExamplesResponse
JSON SCHEMAFrequencyResponse
JSON SCHEMAFrequency
JSON SCHEMAHasCategoriesResponse
JSON SCHEMAHasMembersResponse
JSON SCHEMAHasPartsResponse
JSON SCHEMAHasSubstancesResponse
JSON SCHEMAHasTypesResponse
JSON SCHEMAHasUsagesResponse
JSON SCHEMAInCategoryResponse
JSON SCHEMAInRegionResponse
JSON SCHEMAInstanceOfResponse
JSON SCHEMAInstancesResponse
JSON SCHEMAMemberOfResponse
JSON SCHEMAPartOfResponse
JSON SCHEMAPertainsToResponse
JSON SCHEMAPronunciationResponse
JSON SCHEMAPronunciation
JSON SCHEMARegionOfResponse
JSON SCHEMAResult
JSON SCHEMARhymesResponse
JSON SCHEMASearchResponse
JSON SCHEMASearchResultsMeta
JSON SCHEMASimilarToResponse
JSON SCHEMASubstanceOfResponse
JSON SCHEMASyllablesResponse
JSON SCHEMASyllables
JSON SCHEMASynonymsResponse
JSON SCHEMATypeOfResponse
JSON SCHEMAUsageOfResponse
JSON SCHEMAWordEntry
JSON SCHEMAScroll within the panel for all 36 ·
JSON Structure 36
JSON Structure captures the data shapes in a form built for tooling — a complement to JSON Schema that keeps the model machine-legible.
JSON Structure definitions describing this provider's data shapes.
Words Also Response Structure
JSON STRUCTUREWords Antonyms Response Structure
JSON STRUCTUREWords Definition Entry Structure
JSON STRUCTUREWords Definitions Response Structure
JSON STRUCTUREWords Entails Response Structure
JSON STRUCTUREWords Examples Response Structure
JSON STRUCTUREWords Frequency Response Structure
JSON STRUCTUREWords Frequency Structure
JSON STRUCTUREWords Has Categories Response Structure
JSON STRUCTUREWords Has Members Response Structure
JSON STRUCTUREWords Has Parts Response Structure
JSON STRUCTUREWords Has Substances Response Structure
JSON STRUCTUREWords Has Types Response Structure
JSON STRUCTUREWords Has Usages Response Structure
JSON STRUCTUREWords In Category Response Structure
JSON STRUCTUREWords In Region Response Structure
JSON STRUCTUREWords Instance Of Response Structure
JSON STRUCTUREWords Instances Response Structure
JSON STRUCTUREWords Member Of Response Structure
JSON STRUCTUREWords Part Of Response Structure
JSON STRUCTUREWords Pertains To Response Structure
JSON STRUCTUREWords Pronunciation Response Structure
JSON STRUCTUREWords Pronunciation Structure
JSON STRUCTUREWords Region Of Response Structure
JSON STRUCTUREWords Result Structure
JSON STRUCTUREWords Rhymes Response Structure
JSON STRUCTUREWords Search Response Structure
JSON STRUCTUREWords Search Results Meta Structure
JSON STRUCTUREWords Similar To Response Structure
JSON STRUCTUREWords Substance Of Response Structure
JSON STRUCTUREWords Syllables Response Structure
JSON STRUCTUREWords Syllables Structure
JSON STRUCTUREWords Synonyms Response Structure
JSON STRUCTUREWords Type Of Response Structure
JSON STRUCTUREWords Usage Of Response Structure
JSON STRUCTUREWords Word Entry Structure
JSON STRUCTUREScroll within the panel for all 36 ·
Examples 36
Real request and response payloads are what turn a spec from abstract into obvious — and they're one of the twelve things an agent needs to call an API correctly on the first try.
Example request and response payloads for these APIs.
Words Also Response Example
EXAMPLEWords Frequency Example
EXAMPLEWords Pronunciation Example
EXAMPLEWords Result Example
EXAMPLEWords Syllables Example
EXAMPLEWords Word Entry Example
EXAMPLEScroll within the panel for all 36 ·
Security Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Agentic Access 1
An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.
Recommended x-agentic-access execution contracts for AI agents.
Use Cases 8
What developers actually build with this provider — captured so the catalogue answers 'what is this for', not just 'what does this expose'.
What developers build with this provider.
Dictionary and Thesaurus Applications
Power dictionary, thesaurus, and "word of the day" applications with definitions, synonyms, and related words.
Word Games and Puzzles
Drive crossword, Scrabble-style, and anagram games with filtered word search, rhymes, and difficulty-tunable random word selection.
Writing and Editing Tools
Build grammar, style, and writing assistants that suggest synonyms, antonyms, and frequency-aware alternatives.
Language Learning and Education
Provide IPA pronunciation, syllable splits, frequency, and example sentences for ESL and vocabulary-building apps.
NLP and Text Enrichment
Enrich downstream NLP pipelines with hypernyms, hyponyms, meronyms, and domain labels for entity expansion.
Voice and Speech Applications
Use IPA pronunciation and syllable data for speech synthesis, ASR vocabulary tuning, and pronunciation coaching.
Chatbots and Conversational Agents
Disambiguate user input by mapping words to their senses, hypernyms, and categories at runtime.
Content Generation and Rewriting
Drive paraphrasing and content-variation engines with synonym, similar-to, and pertains-to relationships.
Scroll within the panel for all 8 ·
Integrations 3
Pre-built integrations with other platforms tell you where this provider already fits in a stack.
Pre-built integrations with other platforms and tools.
RapidAPI
Words API is distributed, authenticated, and metered through the RapidAPI marketplace.
WordNet
Lexical relationships (typeOf, hasParts, memberOf, etc.) follow the WordNet relational model.
Subtitle Corpora
Frequency data is derived from large English movie and television subtitle corpora (see WordsAPI/wordfrequencies on GitHub).
Solutions 5
Packaged solutions the provider offers on top of the raw API surface.
Packaged solutions this provider offers.
Free Tier
2,500 requests per day at no charge for prototyping, students, and small projects.
Pro
$10 / month, 25,000 requests per day for production applications and games.
Ultra
$49 / month, 250,000 requests per day for high-volume consumer applications.
Mega
$89 / month, 500,000 requests per day for very high-volume production workloads.
Data Purchase
One-time $629 purchase of the full Words API dataset for local hosting.
Resources
Every other property we hold for Words API — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 1
Portal, sign-up, and the first successful call
Documentation 1
Reference material describing how the API behaves
Agent Surfaces 1
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 3
Pagination, idempotency, versioning, errors, and events
Build 2
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Operate 2
Status, limits, changes, and where to get help
Commercial 3
Pricing, plans, and the legal terms of use
Company 2
The organization behind the API
Other 2
Properties that don't map to a standard resource type
← All providers · Data indexed from github.com/api-evangelist/words · machine-readable index on apis.io