Ranked by the provider's API Evangelist rating — the Kin Score is scored per provider, not per API, so every API of a provider shares its band. How the rating works →

Exemplar 17 Complete, well-documented, and agent-ready

Power Platform Connectors APIAPI for custom and certified connectors that extend Power Platform capabilities across Power Apps, Power Au...76.4 Arazzo Specification (Redocly Tooling)Arazzo is the OpenAPI Initiative's specification for describing multi-step API workflows; Redocly is a prim...74.6 CData Connect AI OpenAPI APIGenerates and returns an OpenAPI document describing the data in a Connect AI workspace, so no-code and low...74.6 Redocly CLIRedocly CLI is an open-source command-line tool for working with OpenAPI descriptions, developer portals, a...74.6 Redocly RedocRedoc is the open-source engine that renders API reference documentation from OpenAPI definitions with a th...74.6 0xArchive REST APICurrent and historical market data across Hyperliquid core, Spot, HIP-3, HIP-4, and Lighter. Direct market-...72.7 Snyk OpenAPI APIThe OpenAPI specification for this service.71.3 Act! Web APIJSON-based REST API for the Act! CRM database exposing contacts, companies, groups, opportunities, tasks, a...70.2 Stoplight CLIThe Stoplight CLI enables programmatic linting of API descriptions and pushing analysis results to the Stop...69.7 Stoplight ElementsElements is an open-source toolkit for building beautiful, interactive API documentation from OpenAPI speci...69.7 Stoplight PlatformStoplight Platform is a SaaS collaborative API design and documentation management tool providing a visual ...69.7 Stoplight PrismPrism is an open-source HTTP mock and proxy server that turns any OpenAPI v2/v3 or Postman Collection file ...69.7 Stoplight SpectralSpectral is an open-source JSON and YAML linter for creating automated API style guides and governance rule...69.7 Stoplight StudioStoplight Studio is the visual API design and technical writing editor included in the Stoplight Platform. ...69.7 Tvarka Sign APIMachine channel for Tvarka Sign: post a document and a list of signers and Tvarka runs its ordinary qualifi...68.9 Agorapulse Open APIThe Open API API from Agorapulse — 0 operation(s) for open api.67.1 Agorapulse Open APIThe OpenAPI API from Agorapulse — 1 operation(s) for openapi.67.1

Strong 28 Solid coverage with minor gaps

Clerk OpenAPI SpecificationsPublic repository of OpenAPI specifications for Clerk's APIs, used as the source for generated SDKs and doc...65.8 Dentsply Sirona Intraoral Imaging Filters APIA 9-operation OpenAPI 3.0.1 contract for applying Dentsply Sirona's Select, Supreme and AE image filters to...65.6 Dentsply Sirona Intraoral Imaging Modality APIA 17-operation OpenAPI 3.0.1 contract for acquisition and control of Dentsply Sirona intraoral sensors. Dev...65.6 Intraoral Exposure APIA 4-operation, read-only OpenAPI 3.0.0 contract for exchanging intraoral X-ray exposure dose information, s...65.6 TranscriptFetch REST APIREST API (current version v2, path-prefixed) for fetching timestamped transcripts from YouTube, TikTok, Ins...64.7 StayingAPI Agent SkillsPublished portable SKILL.md agent skill in the stayingapi/travel-skills GitHub repo, referenced from the SD...63.6 StayingAPI MCP ServerHosted MCP server (Streamable HTTP, OAuth 2.1/PKCE) exposing 7 read-only tools mapping 1:1 to the REST endp...63.6 Custom Connectors APICustom connectors allow you to create wrappers around REST or SOAP APIs for use in Power Apps, Power Automa...60.8 Routebase APIThe public, customer-committed part of the Routebase API — CLI-driven CI test runs, spec versioning and pro...60.8 Geneos Netprobe REST APIOpenAPI 3.0 REST plug-in on the Geneos Netprobe. Third-party applications PUT JSON to create or update data...59.5 Zuplo Openapi APIThe Openapi API from Zuplo — 1 operation(s) for openapi.59.4 Bloomberg BLPAPI CoreThe Bloomberg Open API (BLPAPI) Core — the foundational service-oriented, socket-based API used by the Desk...59.0 Corva Data APIThe Corva Data API serves the records stored in Corva datasets — one-second operational data, engineering c...59.0 Windmill openapi APIThe openapi API from Windmill — 2 operation(s) for openapi.58.0 Scanverity Resolution APIREST API (OpenAPI 3.1, contract v1.3.0-private-beta) for resolution-risk assessment on prediction markets. ...57.0 ReefAPI MCP ServerHosted MCP server over streamable-HTTP with 5 discovery-first tools (search_engines, get_catalog, get_engin...56.9 ReefAPI REST APIPOST-based REST/JSON API fronting a catalog of web-data engines. Auth via x-api-key header; uniform {ok,dat...56.9 FUNDify — RIS Synergy Funding APITU Wien's own OpenAPI-described contract, and the only one in this repository. FUNDify publishes Austrian f...56.2 DeveloperHub Documentation PlatformDeveloperHub provides a hosted platform for creating developer documentation including API references auto-...56.1 DeveloperHub References APIUploads, downloads and publishes the OpenAPI specification behind an API reference — the CI/CD surface, and...56.1 Cisco Intersight Openapi APIThe openapi API from Cisco Intersight — 10 operation(s) for openapi.55.8 Treblle API DocumentationTreblle API Documentation automatically generates real-time API documentation from live API traffic and SDK...55.8 Treblle API InsightsTreblle API Insights is a free governance tool that evaluates OpenAPI specifications, providing scores from...55.8 RoxyAPI REST API v2Production REST API covering 14 spiritual intelligence domains with 210+ endpoints under a single API key, ...55.2 Adanos Market Sentiment APIRESTful JSON API grouping five sentiment services (Reddit Stocks, X.com Stocks, Stock News, Polymarket Stoc...54.3 Arazzo EngineOpen-source Python engine that executes Arazzo workflow specifications alongside OpenAPI operation definiti...54.3 IBM WebSphere OpenAPI APIMicroProfile OpenAPI documentation endpoints54.3 VMware Cloud Director OpenAPIModern RESTful API for VMware Cloud Director defined using OpenAPI standards providing cloud service delive...54.3

Developing 52 Usable, with meaningful gaps to close

Thin 47 Limited public surface area

FernFern transforms a single API source of truth (OpenAPI, AsyncAPI, Protobuf, OpenRPC, or the Fern Definition ...38.7 Xano Generated User APIsThe REST APIs that Xano users build visually. Each API group is served at its own /api:{token} path on the ...38.6 KiotaKiota generates strongly-typed, lightweight API clients from OpenAPI descriptions in C#, Dart, Go, Java, PH...38.1 Kubescape In-Cluster Component API (Open Source)The open-source Kubescape Operator's in-cluster components (storage, kubevuln, gateway, operator, node-agen...37.5 Mosaic Open APIThe Mosaic Open API exposes the workforce, project, and financial data Mosaic manages so firms can build cu...37.5 OWASP ZAP openapi APIThe openapi API from OWASP ZAP — 2 operation(s) for openapi.37.5 Ambassador Blackbird API Development PlatformBlackbird is an API development platform that helps developers design, build, test, and manage APIs with AI...36.7 Ambassador Edge Stack Developer PortalThe Ambassador Edge Stack Developer Portal automatically detects and publishes API documentation, serving a...36.7 NASA Earthdata OpenAPI APIThe OpenAPI API from NASA Earthdata — 1 operation(s) for openapi.35.7 Ignition Gateway REST APIThe Ignition Gateway REST API (available in Ignition 8.3+) provides an OpenAPI- compliant HTTP interface to...35.4 Kareo Clinical Open APIThe Kareo Clinical Open API provides REST-based access to EHR clinical data, exposing patient clinical reco...34.5 UNIverse Research Information System APIThe REST backend of UNIverse (universe.unibas.ch), the University of Basel's research information system, a...34.4 Open Charge Map Openapi APIThe Openapi API from Open Charge Map — 1 operation(s) for openapi.34.1 RefitterRefitter is a .NET source generator and CLI tool that produces Refit HTTP client interfaces from OpenAPI 2....34.1 Dredd API Testing FrameworkDredd is an open-source language-agnostic command-line tool for validating API documentation written in Ope...34.0 SchemathesisSchemathesis is a property-based testing tool for web APIs. It reads OpenAPI or GraphQL schemas and automat...34.0 LAPIS SpecificationThe LAPIS specification defines a token-minimal, LLM-native format for describing HTTP APIs. A LAPIS docume...33.9 Country Calling Codes APIRead-only JSON API for country calling code lookup, phone number formatting, analysis, batch normalization,...33.1 OgenThe ogen code generator. Invoked as a build-time CLI against a local OpenAPI v3 document — `ogen [options] ...33.1 SchemathesisSchemathesis is a property-based API testing tool that automatically generates test cases from OpenAPI and ...33.0 Dredd APICommand-line HTTP API testing framework that validates API implementations against API Blueprint or OpenAPI...32.9 Apicurio CodegenApicurio Codegen generates Java JAX-RS server stubs and client code from OpenAPI specifications, enabling d...32.6 Apicurio Data ModelsApicurio Data Models is a Java and TypeScript library for parsing, validating, and manipulating OpenAPI and...32.6 Apicurio RegistryApicurio Registry is a high-performance, runtime registry for schemas and API designs. It stores and manage...32.6 Apicurio StudioApicurio Studio is a visual, zero-code API design tool for creating and editing OpenAPI and AsyncAPI specif...32.6 Filecoin HTTP REST APIOpenAPI-specified HTTP REST interface for Filecoin nodes, covering chain resources (tipsets, blocks, execut...32.6 what3words API Docs and OpenAPI RepositoryPublic repository hosting the OpenAPI specification, LLM files, and reference material for the what3words P...32.4 TypeSpec OpenAPI EmitterThe TypeSpec OpenAPI emitter converts TypeSpec definitions to OpenAPI 3.0 specifications. It supports HTTP ...32.2 Hanyang University Open API Developer CenterHanyang University's own Open API platform, built and run by the university rather than bought from a vendo...31.4 Vert.x OpenAPIVert.x OpenAPI provides OpenAPI 3.1 specification support for Vert.x, enabling contract-driven API developm...31.4 Oapi-CodegenCommand-line tool and Go library that converts OpenAPI 3.0 and 3.1 specifications into Go server-side, clie...31.2 LayerZero openapi APIThe openapi API from LayerZero — 1 operation(s) for openapi.31.0 Sourcegraph REST APIVersioned external REST API introduced in Sourcegraph 7.0 and intended as the stable integration surface go...30.9 Lumen OpenAPI Services (Level 3 legacy)The Level 3 / Lumen OpenAPI Services portal provided OpenAPI-described REST services such as the Lumen Loca...30.7 OpenAPI SpecificationThe OpenAPI Specification (formerly Swagger Specification) is a language-agnostic standard for describing H...30.1 Swagger CodegenSwagger Codegen generates server stubs, client SDKs, and API documentation from OpenAPI specifications in o...30.1 Swagger EditorSwagger Editor is a browser-based editor for writing and validating OpenAPI and AsyncAPI specifications wit...30.1 Swagger ParserSwagger Parser (swagger-parser) is a JavaScript library for parsing, validating, and dereferencing OpenAPI ...30.1 Swagger UISwagger UI renders OpenAPI specifications as interactive API documentation, allowing developers to explore ...30.1 Morgan Stanley API Platform (REST)The institutional REST APIs on the Morgan Stanley API Platform let onboarded clients and third-party partne...29.3 AutoRest CoreThe AutoRest Core package (@autorest/core) is the central engine that orchestrates code generation from Ope...29.0 42Crunch API Security AuditThe 42Crunch API Security Audit performs automated static analysis of API definitions (OpenAPI 2, 3.0, 3.1 ...28.8 Liblab MCP GeneratorGenerates a complete Model Context Protocol (MCP) server from an OpenAPI, Swagger, or Postman spec so AI ch...28.8 Liblab SDK GeneratorCloud-based generator that produces customizable, type-safe SDKs in seven target stacks (TypeScript, Python...28.8 ReDocReDoc is an open-source API documentation renderer for OpenAPI specifications, originally created by Rebill...27.1 Quarkus OpenAPI APIThe OpenAPI API from Quarkus — 2 operation(s) for openapi.26.4 BetTip Draws APIKeyless, CORS-open REST API serving lottery draw results as JSON and CSV across UK49s, Gosloto, SA National...26.3

Emerging 49 Early or largely undocumented

Chainguard Unified API SpecThe unified Chainguard API specification combines API v1 and v2 definitions in a single reference, useful f...25.2 NSwagNSwag is an open source .NET toolchain for generating C# and TypeScript API clients and Swagger/OpenAPI spe...24.2 Helidon OpenAPI APIThe OpenAPI API from Helidon — 1 operation(s) for openapi.24.0 OpenAPI GeneratorOpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation a...23.9 VacuumVacuum is the world's fastest OpenAPI linter written in Go. It processes API specifications at lightning sp...23.6 SpectralSpectral is a flexible JSON/YAML linter and style guide enforcer with built-in support for OpenAPI (v3.1, v...23.4 MediaRuntime APIVersioned REST API (under /v1) for media-processing jobs, reports/analysis, reusable recipes, uploads/water...23.1 NEXON Open APIProgrammatic access to per-game data (character, ranking, match, and metadata) for Nexon titles. Authentica...22.6 OpenAPI Specification (OAS)The OpenAPI Specification (formerly Swagger) is the dominant industry standard for describing HTTP-based RE...22.5 ISO 20022 API Resources CatalogueThe ISO 20022 API Resources Catalogue, governed by the API Standards Evaluation Group (APISEG), provides re...22.1 Coupang Open APIThe Coupang Open API is a RESTful seller (vendor) API for managing the full marketplace lifecycle including...21.8 Zalando RESTful API and Event GuidelinesThe canonical open community style guide. Maintained by Zalando's API Guild and widely cited as the referen...21.4 Flotiq APIAuto-generated RESTful and GraphQL APIs derived from user-defined content type definitions, enabling full C...21.1 Optic CLIThe Optic CLI provides OpenAPI diffing, linting and breaking-change detection from the command line, compar...21.1 Apicurio RegistryRed Hat's open-source API/schema registry that stores and validates OpenAPI, AsyncAPI, JSON Schema, Avro, P...20.8 OpticOptic catches breaking changes and applies lint rules to OpenAPI specs, generating OpenAPI from real traffi...20.8 Postman API GovernancePostman Spec Hub's governance engine applies linting rules to OpenAPI 2.0, 3.0, and 3.1 specifications, sur...20.8 Redocly CLIRedocly's `lint` command identifies and reports problems in OpenAPI, AsyncAPI, Arazzo, or Open-RPC descript...20.8 Speakeasy LinterSpeakeasy's OpenAPI validator with 90+ built-in rules across six categories — SDK generation, spec correctn...20.8 SpectralStoplight's flexible JSON/YAML linter for creating automated style guides, with baked-in support for OpenAP...20.8 Sweater CombSnyk's TypeScript ruleset built on Optic CI that enforces consistency standards across OpenAPI specificatio...20.8 VacuumA Go-based, ultra-fast OpenAPI linter inspired by Spectral and fully compatible with existing Spectral rule...20.8 SpecLynxStop wrestling with OpenAPI specs. SpecLynx OpenAPI Toolkit delivers the most effective way to author and m...20.7 SpecLynx ApiDOMA unified semantic parsing engine that underpins all SpecLynx products. ApiDOM parses OpenAPI, AsyncAPI, Ar...20.7 SpecLynx CLIA command-line interface for overlay operations, dereferencing, bundling, format conversion (JSON/YAML), an...20.7 SpecLynx EditorA browser-based OpenAPI editor with real-time validation, smart autocompletion, and live preview. No instal...20.7 SpecLynx Language ServiceAn LSP-compatible npm library (@speclynx/apidom-ls) providing 13 intelligent editing capabilities for API d...20.7 SpecLynx OpenAPI ToolkitA VS Code extension providing semantic editing, real-time validation, linting, and live preview for OpenAPI...20.7 Konfig OpenAPI LintingCapability area (endpointsModeled). A configurable linter that inspects an OpenAPI Specification for errors...20.4 Konfig SDK Generation Platform (Sunset)Konfig's developer platform for generating, validating, and publishing SDKs, API reference documentation, a...20.4 DreddDredd is a language-agnostic command-line tool for validating an API description document against a backend...20.2 OpenAPI VersioningOpenAPI handles versioning through the info.version field (using SemVer), the deprecated flag on individual...20.2 FastAPI FrameworkModern, fast web framework for building APIs with Python based on standard Python type hints.20.0 Optic APIOptic is a developer tool that uses API specifications as the source of truth for testing. It tracks specif...20.0 SpectralSpectral is an open-source JSON/YAML linter and specification validator. It evaluates OpenAPI, AsyncAPI, an...20.0 Swagger EditorSwagger Editor is an open-source web-based editor for designing OpenAPI specifications that double as test ...20.0 Paradox Open APIParadox's customer- and partner-facing Open API used to build custom integrations with ATS, HRIS, and opera...19.9 FastMCP OpenAPI and FastAPI IntegrationFastMCP can generate an MCP server directly from an existing OpenAPI 3.x description or a FastAPI applicati...19.7 Stainless Platform APIThe Stainless Platform API is a REST API for programmatically managing Stainless projects, branches, and SD...19.3 OpenAPI SpecificationThe OpenAPI Specification (OAS) defines a standard, language-agnostic interface to RESTful APIs which allow...18.9 OpenAPI SpecificationThe OpenAPI Specification (OAS) defines a standard, programming language-agnostic interface description for...17.9 DapperDoxDapperDox is an open-source API documentation generator that renders beautiful, customizable reference docs...17.3 Connexion Python FrameworkConnexion is a contract-first Python web framework that loads an OpenAPI specification and routes requests ...17.2 LoopBackLoopBack is a highly extensible Node.js and TypeScript framework for building APIs and microservices with b...17.2 PortmanPortman is an open source CLI tool that auto-generates Postman collections with contract and variation test...14.9 JD Cloud OpenAPIJD Cloud OpenAPI is the programmatic control plane for JD Technology's public cloud — compute (VM), storage...13.2 API Insights AnalysisAPI Insights analyzes OpenAPI specifications (OAS v3, JSON or YAML) and produces detailed scorecards across...13.0 FastAPIModern, fast web framework for building APIs with Python 3.7+.11.9 OasdiffOasdiff is an open-source tool for detecting breaking changes and generating changelogs from OpenAPI specif...11.2

Minimal 1 Almost no public developer surface

X-Road (Straumurinn) API CatalogueIceland's X-Road data-exchange layer (Straumurinn). Government-to-government REST services that publish Ope...7.2

Companies reaching this through an API (64)

These companies publish an API, specification or operation carrying “OpenAPI” but do not classify their business under it. Listed unranked and kept out of the count above, because one tagged operation is not a statement about what a company does.

Act! CRM Agorapulse Aklivity Ambassador American Financial Group API Specifications APIContext APIMatic Bloomberg CData CenturyLink (Lumen Technologies) Chainguard Cisco Intersight Citrix NetScaler Clerk Corva AI Dentsply Sirona Diebold Nixdorf Dream Sports FastMCP Filecoin Flotiq Helidon IBM WebSphere Inductive Automation ISO 20022 Kareo Kubescape LayerZero MediaRuntime Microsoft Power Apps Microsoft Power Platform APIs Morgan Stanley Mosaic MuleSoft NASA Earthdata Onshape Open Charge Map OpenAPI OpenJS Foundation OWASP ZAP Paradox Python Standard Library and Popular Quarkus REST Restate Snyk Sourcegraph Speakeasy Test First

Show all 64 companies ↓

Test Scripts Treblle Trieve TU Wien Twenty University of Basel University of Warsaw Versioning Protocols Vert.x VMware what3words Windmill Xano Zuplo

Score breakdown

Frequency

68.8

log-scaled weighted occurrences

Breadth

3.9

spread across providers

Quality lift

46.4

mean composite of providers using it

Cohesion

11.5

strength of nearest seed neighbor

Where this tag comes from

Provider tag143

Api tag196

Openapi tag17

Openapi op tag23

Cohort brief

Auto-generated

The 140 providers in the APIs.io catalog tagged OpenAPI, scored on the Kin Score. Every figure below is computed from the catalog — nothing here is written.

Providers

140

all scored

Mean Kin Score

41.4

+17.5 vs catalog 23.9

Mean Agent Readiness

+14 vs catalog 12

Spread

7.2–90

median 40.6 · σ 16.9

How the 140 split by band

Exemplar 9Strong 27Developing 37Thin 36Emerging 30Minimal 1

Facet averages, against the whole catalog

Facet	This cohort	Catalog	Difference	Scored
Developer Ergonomics	45.2	23.4	+21.8	140
Contract Quality	39.8	19.8	+20	140
Operational Transparency	33.6	14	+19.6	140
Access Clarity	40.7	26.5	+14.2	140
Contract Governance	16	6.4	+9.6	140
Discoverability	69.7	61.2	+8.5	140

A facet is averaged over the members that carry it, not over the whole cohort — the “Scored” column is that count. Averaging an absent facet as zero would score our own coverage gaps as the providers’ posture.

What this cohort publishes

Artifact	This cohort	Catalog	Difference
MCP server (any)	34%	10%	+24
MCP server (first-party)	35%	13%	+22
Agent Skills	0%	0%	0
OAuth scopes	19%	11%	+8
Security	96%	97%	-1
Arazzo workflows	5%	2%	+3
Governance rules	32%	14%	+18

mcp_pct counts any mcp/ artifact including ones API Evangelist derived from the provider OpenAPI; mcp_first_party_pct counts only servers the provider publishes. Prefer the latter.

Top by Kin Score

1 APIs.io 90
2 OpenMercantil 88.2
3 Zoho CRM 75.8
4 Redocly 74.6
5 0xArchive 72.7
6 Postman 72.5
7 Cvent Event Cloud 69.9
8 Stoplight 69.7
9 Tvarka ATK API 68.9
10 TranscriptFetch 64.7

Work with this as data

Every tag here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for tags

7 MCP tools reach this

find_tagsBrowse and filter every tag in the catalog.
get_cohortThis tag as a scored cohort — every provider carrying it, with scores.
cohort_statsPRO — the distribution across this tag: mean, median, band split, adoption rates.
cohort_rankingsPRO — the leaderboard, on composite AND agent-readiness axes.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

All 92 tools →

Call it yourself

curl for this page

This tag

curl "https://apis.io/api/v1/tags/openapi"

All tags

curl "https://apis.io/api/v1/tags?limit=25"

As a scored cohort

curl "https://apis.io/api/v1/cohorts/tag/openapi"

The distribution (Pro)

curl "https://apis.io/api/v1/cohorts/tag/openapi/stats" \
  -H "X-API-Key: $APIS_IO_KEY"

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OpenAPI

Providers using this tag (143)

APIs with this tag (194)