Feature

OpenAPI Specification

A machine-readable OpenAPI/Swagger contract.

60 providers 993 APIs 60 declared variants

The API ships an OpenAPI (or Swagger) description, which unlocks generated clients, mocks, linting, and import into every major API tool. The single highest-leverage artifact a provider can publish.

60 API providers on the APIs.io network offer openapi specification. The highest-rated are Postman, Appian, Socket, Canvas LMS, Commerce Layer.

Providers

Ranked by API Evangelist rating — Exemplar and Strong are expanded by default.

Exemplar 14 Complete, well-documented, and agent-ready
Postman Postman is the world's leading API platform, used by 35+ million developers to design, build, test, documen... 39 APIs 75.8 Appian Appian is a low-code automation platform that accelerates the creation of high-impact business applications... 12 APIs 73.8 Socket Socket is a developer-first supply-chain security platform that protects applications from malicious depend... 19 APIs 72.9 Canvas LMS Canvas is the open, AGPLv3-licensed learning management system created and maintained by Instructure, Inc. ... 16 APIs 71.7 Commerce Layer Commerce Layer is the headless, multi-market commerce API used by global brands to sell everywhere — web, m... 148 APIs 69.5 S&P Global S&P Global (NYSE SPGI) is the parent of S&P Global Ratings, S&P Global Market Intelligence, S&P Dow Jones I... 9 APIs 69.0 Raygun Raygun is an application monitoring platform that combines Crash Reporting, Real User Monitoring (RUM), and... 15 APIs 68.7 APIMatic APIMatic is a developer experience platform for APIs that specializes in automated SDK generation, API docu... 6 APIs 68.6 Truework Truework operates a unified income and employment verification platform for mortgage lenders, credit unions... 5 APIs 68.2 Amadeus Amadeus for Developers is the self-service developer program from Amadeus IT Group, the leading technology ... 26 APIs 68.1 Auth0 Auth0 (now part of Okta) is a leading identity-as-a-service platform providing authentication and authoriza... 76 APIs 68.0 Pinecone With its vector database at the core, Pinecone is the leading knowledge platform for building accurate, sec... 9 APIs 67.8 Adafruit IO Adafruit IO is a cloud Internet of Things platform from Adafruit Industries built for makers, hobbyists, st... 12 APIs 67.6 Rigetti Computing Rigetti Computing (Nasdaq, RGTI) is a Berkeley, California-based quantum computing company building superco... 11 APIs 67.0
Strong 12 Solid coverage with minor gaps
PolyAPI Poly, built using cutting-edge AI and Kubernetes-native technology, accelerates development and simplifies ... 10 APIs 65.2 Speakeasy The platform to Build APIs your users love. Best in class API tooling for robust SDKs, API docs, Terraform ... 20 APIs 64.4 Microsoft Azure Quantum Microsoft Azure Quantum is Microsoft's cloud quantum computing service — an open, multi-vendor platform tha... 8 APIs 64.3 Soracom Soracom is a global IoT cellular connectivity and platform provider headquartered in Tokyo, founded in 2014... 45 APIs 63.9 IonQ IonQ (NYSE IONQ) is a College Park, Maryland-based public trapped-ion quantum computing company. IonQ desig... 7 APIs 62.1 Lichess Lichess is a free, ad-free, open-source online chess server operated by a French nonprofit and powered enti... 23 APIs 61.7 TIDAL TIDAL is a high-fidelity music streaming service owned by Block (Square's parent, acquired 2021) offering H... 65 APIs 61.7 LALAL.AI LALAL.AI is an AI-powered audio separation and voice technology platform operated by OmniSale GmbH. It uses... 4 APIs 61.4 StackOne StackOne is an AI-powered embedded integration platform as a service (iPaaS) designed to simplify and accel... 33 APIs 60.4 Continue Continue is the open-source AI code assistant for VS Code and JetBrains, distributed under Apache 2.0. The ... 5 APIs 58.9 Apache OFBiz Apache OFBiz is an open-source enterprise resource planning (ERP) system providing a suite of integrated bu... 2 APIs 58.0 TheTVDB TheTVDB is a community-driven television and movie metadata database founded in 2006. It supplies structure... 29 APIs 56.8
Developing 11 Usable, with meaningful gaps to close
Jetic Jetic is the first and only cloud-native API & Integration Platform based on Apache Camel. An iPaaS solutio... 5 APIs 55.0 Octopus Energy Octopus Energy is a UK-founded retail energy supplier and the parent of Kraken Technologies, the AI-powered... 9 APIs 52.9 automation-anywhere Automation Anywhere is an enterprise robotic process automation (RPA) platform that enables organizations t... 22 APIs 52.3 Trino Trino is an open-source, distributed SQL query engine built for lightning-fast analytics over large, hetero... 2 APIs 51.5 APIs.guru APIs.guru is an open source, community-driven directory of public REST API definitions in OpenAPI 2.0/3.x f... 1 API 49.4 API-Fiddle API-Fiddle is an interactive, collaborative API design platform for creating professional APIs based on Ope... 5 APIs 47.1 Loops Loops is a modern email platform purpose-built for software companies, combining product, marketing, and tr... 12 APIs 46.6 Vert.x Eclipse Vert.x is a toolkit for building reactive applications on the JVM, providing support for multiple l... 7 APIs 46.5 NOAA — National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (NOAA) is the United States scientific and regulatory a... 24 APIs 43.1 Wowza Wowza is a Denver, Colorado-based video streaming infrastructure provider that has been simplifying live an... 48 APIs 43.1 42Crunch 42Crunch is a leading API security company that specializes in protecting and securing APIs. They provide i... 6 APIs 42.1
Thin 17 Limited public surface area
Test First A software development approach where tests are written before the implementation code, ensuring code quali... 5 APIs 41.5 Langflow Langflow is an open-source low-code visual builder for AI agents, RAG pipelines, and LangChain-based workfl... 15 APIs 41.1 Lex Machina Lex Machina is a legal analytics platform owned by LexisNexis that transforms raw court documents and docke... 21 APIs 40.8 Ron Swanson Quotes A community-built, open source HTTP API that returns Ron Swanson quotes from the NBC television series Park... 1 API 40.6 Unity Unity is a real-time 3D content creation platform — the Unity engine powers cross-platform games, simulatio... 19 APIs 40.6 Marqo Marqo is an open-source, multimodal vector search engine that lets developers index text and images, genera... 7 APIs 38.8 Krea Krea is a real-time AI creative suite that lets designers, filmmakers, brand teams, and everyday creators g... 7 APIs 38.3 APIClarity APIClarity is an open source API security and observability tool that analyzes API traffic to reconstruct O... 4 APIs 36.6 AutoRest AutoRest is an open source tool from Microsoft (MIT License) that generates client libraries for accessing ... 6 APIs 35.8 LAPIS LAPIS (Lightweight API Specification for Intelligent Systems) is a compact, LLM-native API description form... 1 API 35.3 ApiNotes ApiNotes is an interactive API documentation tool that generates developer portals with live endpoint testi... 1 API 32.8 AsyncAPI AsyncAPI is a Linux Foundation project that improves the state of event-driven architectures by providing a... 8 APIs 32.5 Pie Insurance Pie Insurance is a Washington, DC and Denver-based insurtech founded in May 2017 that makes commercial insu... 7 APIs 32.5 SpecLynx SpecLynx provides enterprise-ready API tooling for authors and maintainers of OpenAPI, AsyncAPI, and Arazzo... 6 APIs 31.6 Deutsche Telekom Deutsche Telekom AG is Europe's largest telecommunications operator, headquartered in Bonn, Germany, servin... 50 APIs 31.1 Apiary Apiary is an API design and documentation platform, now part of Oracle Cloud Infrastructure. With 486,000+ ... 2 APIs 30.6 Volvo Cars Volvo Cars is a Swedish premium automotive OEM (headquartered in Gothenburg, owned by Geely) that operates ... 4 APIs 28.6
Emerging 5 Early or largely undocumented
Cresta Cresta is a Mountain View / Sunnyvale, California contact center AI company spun out of the Stanford AI Lab... 25.5 Events Event-driven APIs catalog. Documents the landscape of brokers, streaming platforms, schema registries, and ... 18 APIs 20.6 API Insights API Insights is a free online tool powered by Treblle that provides advanced API analysis and monitoring by... 1 API 18.8 Quantinuum Quantinuum is an integrated quantum computing company formed by the 2021 merger of Honeywell Quantum Soluti... 9 APIs 17.2 FastMCP FastMCP is the fast, Pythonic framework for building Model Context Protocol (MCP) servers, clients, and app... 6 APIs 17.1
Minimal 1 Almost no public developer surface
MISMO MISMO — the Mortgage Industry Standards Maintenance Organization — is the standards development body for US... 8.5

What Providers Actually Declared

This feature is a canonical term. These are the free-text strings providers wrote in their own apis.yml that map onto it.

5 public REST OpenAPI surfaces (LLM-ready, Extract, NERD, Scribe v1 batch, Scribe v2 batch)API Contract DefinitionAsyncAPI DescriptionAsyncAPI SpecificationAuto-generated soracom CLI built directly from the OpenAPI specBuilt-in OpenAPI 3.0 generator via the `rake doc:openapi` task using swagger_yardConnected Vehicle API v2 — read vehicle status, diagnostics, statistics, and metadata, and send commands (lock/unlock, climate start/stop, flash lights, sound horn, engine start/stop) backed by a public OpenAPI specification.Deterministic OpenAPI ConversionFastAPI runtime exposing live `/openapi.json` and Swagger UI at `/docs`FastAPI-based REST API with OpenAPI 3.1 spec served at /docs and /openapi.json on every deploymentFull OpenAPI 3.1 specification with 185 operations across 23 tags published at github.com/lichess-org/apiGenerate OpenAPIGitHub-hosted Swagger documentationHybrid REST + gRPC API surface — OpenAPI 3.0 HTTP API for management + gRPC for translation and executionIngest OpenAPIJSON:API (jsonapi.org/format/) compliant Core API with 917 path operations across 130+ top-level resources on a single OpenAPI 3.1 specKraken developer portal at developer.octopus.energy with REST API Reference generated from an OpenAPI specificationLive OpenAPI spec served from https://api.socket.dev/v0/openapiManagement API (OpenAPI 3.1 Beta, 221 paths, 2,567 schemas)National Weather Service api.weather.gov — alerts (CAP), gridded forecasts, observations, aviation (SIGMETs/AIRMETs/TAFs), radar, zones, points, glossary — 66 documented endpoints in OpenAPI 3.9.2Official OpenAPI 3.1 spec served at /api/v1/openapi.json with Swagger-style explorer at /api/v1/docs/Open OpenAPI Specifications RepositoryOpenAPIOpenAPI Contract SecurityOpenAPI Contract ValidationOpenAPI DirectoryOpenAPI ExportOpenAPI Linter GitHub AppOpenAPI ProcessingOpenAPI Spec ReconstructionOpenAPI SupportOpenAPI ToolsOpenAPI Upload and URL InputOpenAPI and FastAPI importOpenAPI spec availableOpenAPI-First DesignOpenAPI/Swagger SupportPostman and Swagger ToolingPostman, OpenAPI-style REST docs, and the UGS CLI as primary integration surfaces for the backend servicesPrepare OpenAPI

Showing 40 of 60 declared variants