OpenAPI.Tools

Tool Types

We've organised everything into categories so you can jump to the section you're interested in.

• Auto Generators: Tools that will take your code and turn it into an OpenAPI Specification document
• Converters: Various tools to convert to and from OpenAPI and other API description formats.
• Data Validators: Check to see if API requests and responses are lining up with the API description.
• Description Validators: Check your API description to see if it is valid OpenAPI.
• Documentation: Render API Description as HTML (or maybe a PDF) so slightly less technical people can figure out how to work with the API.
• DSL: Writing YAML by hand is no fun, and maybe you don't want a GUI, so use a Domain Specific Language to write OpenAPI in your language of choice.
• Gateways: API Gateways and related tools that have integrated support for OpenAPI.
• GUI Editors: Visual editors help you design APIs without needing to memorize the entire OpenAPI specification.
• Learning: Whether you're trying to get documentation for a third party API based on traffic, or are trying to switch to design-first at an organization with no OpenAPI at all, learning can help you move your API spec forward and keep it up to date.
• Miscellaneous: Anything else that does stuff with OpenAPI but hasn't quite got enough to warrant its own category.
• Mock Servers: Fake servers that take description document as input, then route incoming HTTP requests to example responses or dynamically generates examples.
• Monitoring: Monitoring tools let you know what is going on in your API.
• Parsers: Loads and read OpenAPI descriptions, so you can work with them programmatically.
• SDK Generators: Generate code to give to consumers, to help them avoid interacting at a HTTP level.
• Security: By poking around your OpenAPI description, some tools can look out for attack vectors you might not have noticed.
• Server Implementations: Easily create and implement resources and routes for your APIs.
• Testing: Quickly execute API requests and validate responses on the fly through command line or GUI interfaces.
• Text Editors: Text editors give you visual feedback whilst you write OpenAPI, so you can see what docs might look like.

Auto Generators

Tools that will take your code and turn it into an OpenAPI Specification document

Name	Language	v3.2	v3.1	GitHub
🛠️ Speakeasy OpenAPI - An OSS set of packages and tools used by Speakeasy for working with OpenAPI, Arazzo and Overlay Specification documents. Includes CLI tools for validation, bundling, inlining, upgrading, and more. Sponsored	Go, CLI	✅	✅
TypeSpec - Emit OpenAPI specifications from API descriptions defined in the generic, interoperable, and extensible TypeSpec language.	TypeScript	✅	✅
Ballerina OpenAPI tool - The Ballerina OpenAPI tool enables the generation of Ballerina client and service skeleton from provided OpenAPI descriptions and facilitates the creation of OpenAPI v3.x descriptions for given Ballerina services.	Java, Ballerina	❌	✅
drf-spectacular - Sane and flexible OpenAPI 3 schema generation for Django REST framework.	Python	❌	✅
Huma - A modern, simple, fast & flexible micro framework for building HTTP REST/RPC APIs in Go backed by OpenAPI 3 and JSON Schema.	Go	❌	✅
mondrian-framework - Framework for generating OpenAPI 3.1 documents and servers from formal TypeScript definitions of models and services. Includes built-in data validation.	Typescript	❌	✅
oas_rails - Rails engine for generate automatic interactive documentation in your Rails HTTP APIs.	Ruby	❌	✅
OpenAPI DevTools - Browser extension that generates API specs for any app or website	TypeScript	❌	✅
Scramble - Modern Laravel OpenAPI documentation generator. No PHPDoc annotations required.	PHP	❌	✅
ts-oas - Automatically generate OpenAPI specifications from lovely Typescript types.	Typescript	❌	✅

Converters

Various tools to convert to and from OpenAPI and other API description formats.

Name	Language	v3.2	v3.1	GitHub
🛠️ Speakeasy OpenAPI - An OSS set of packages and tools used by Speakeasy for working with OpenAPI, Arazzo and Overlay Specification documents. Includes CLI tools for validation, bundling, inlining, upgrading, and more. Sponsored	Go, CLI	✅	✅
openapi-format - A CLI to format an OpenAPI document by ordering fields in a hierarchical order, with the option to filter out flags, tags, methods, operationIDs; including the option to convert between OpenAPI 3.0, 3.1 and 3.2.	Node.js	✅	✅
// SDK-IT - Generates type-safe client SDKs from OpenAPI specifications and creates OpenAPI specs from TypeScript code.	TypeScript, Dart	❌	✅
@hey-api/openapi-ts - The OpenAPI to TypeScript codegen. Generate clients, SDKs, validators, and more.	TypeScript	❌	✅
allof-merge - Simplify your JsonSchema by combining allOf safely	TypeScript	❌	✅
api - Magical SDK generation from an OpenAPI definition	JavaScript, TypeScript	❌	✅
api-ref-bundler - Bundle all external $ref in Json based API document into single document	TypeScript	❌	✅
APIMatic Transformer - Transform API Descriptions to and from RAML, API Blueprint, OAI v2/v3, WSDL, etc.	SaaS	❌	✅
Ballerina OpenAPI tool - The Ballerina OpenAPI tool enables the generation of Ballerina client and service skeleton from provided OpenAPI descriptions and facilitates the creation of OpenAPI v3.x descriptions for given Ballerina services.	Java, Ballerina	❌	✅
docs - A modern alternative to `go-swagger`. Offers generation and parsing of OpenAPI Specs, depending on the usage.		❌	✅
oas-normalize - Comprehensive tooling for working with OpenAPI definitions.	JavaScript, TypeScript	❌	✅
OData OpenAPI - OData 4.0, 3.0, and 2.0 to OpenAPI v3.1, v3.0, and v2.0 converter	Node.js / XSLT	❌	✅
OpenAPI Filter - Filter internal components from OpenAPI Descriptions	Node.js	❌	✅
OpenAPI TypeScript - Convert static OpenAPI schemas to TypeScript types quickly using pure Node.js. Fast, lightweight, (almost) dependency-free, and no Java/node-gyp/running OpenAPI servers necessary.	TypeScript	❌	✅
openapi-python-client - Generate modern Python clients from OpenAPI 3.0 documents.	Python	❌	✅
openapi-to-hurl - A CLI to convert OpenAPI 3.1 Description Documents to hurl test files	CLI	❌	✅
openapi-to-postman - Convert OpenAPI and Swagger specs to the Postman Collection (v2) format	JavaScript	❌	✅
portman - Port OpenAPI Spec to Postman Collection, with contract & variation tests included!	Node.js	❌	✅
ts-oas - Automatically generate OpenAPI specifications from lovely Typescript types.	Typescript	❌	✅

Data Validators

Check to see if API requests and responses are lining up with the API description.

Name	Language	v3.2	v3.1	GitHub
Membrane API Gateway - Open source API gateway with built-in OpenAPI support. Turn OpenAPI specs into APIs and enforce request and response validation.	Java	✅	✅
openapi-changes - The world's fastest, most beautiful, powerful and detailed OpenAPI change detection tool on earth. Explore every change in An OpenAPI spec. See changes over time, go back into history and see what changed with each commit. Identifies all breaking changes, Powered by libopenapi.	go	✅	✅
OpenAPI::Modern - OpenAPI v3.1, v3.2 validator and JSON Schema validator (drafts 4 through draft2020-12)	Perl	✅	✅
wiretap - Wiretap is a feature packed OpenAPI compliance testing tool. Validate that a client and server are compliant with an OpenAPI spec. Rewrite paths, inject headers, and even host a UI locally to test an OpenAPI implementation.	go	✅	✅
django-contract-tester - Validate Django REST Framework (DRF) and Django Ninja APIs against their OpenAPI specification.	Python	❌	✅
express-openapi-validator - 🦋 Auto-validate API requests and responses in ExpressJS.	JavaScript	❌	✅
fastify-openapi-glue - A plugin for the Fastify webserver to autogenerate a Fastify configuration based on a OpenApi description.	Node.js	❌	✅
Fitting - Library add improve test log for RSpec and WebMock, validate its according to API Blueprint and Open API, show the documentation coverage with log.	Ruby	❌	✅
Huma - A modern, simple, fast & flexible micro framework for building HTTP REST/RPC APIs in Go backed by OpenAPI 3 and JSON Schema.	Go	❌	✅
Kappa - Java validation middleware which can be used to validate HTTP requests and responses against OpenAPI 3.1 definitions based on popular but archived openapi4j. Works with Spring and Vert.x.	Java	❌	✅
Mayhem for API - Probe your REST API with an infinite stream of test cases generated automatically from your OpenAPI specification.	Any	❌	✅
mondrian-framework - Framework for generating OpenAPI 3.1 documents and servers from formal TypeScript definitions of models and services. Includes built-in data validation.	Typescript	❌	✅
OpenAPI HttpFoundation Testing - Validate your HttpFoundation requests and responses (Symfony, Laravel, Drupal...) against OpenAPI definitions	PHP	❌	✅
openapi-core - Validate your requests and responses against an OpenAPI 3 specification and get very verbose and human-readable descriptions of errors. You will receive a deserialized object along with validation result, so you won't need to deserialize it twice.	Python	❌	✅
openapi-data-validator - Validate API requests against an OpenAPI schema. Lightweight, focused, and integrates with any framework	Node.js/ Javascript	❌	✅
openapi-psr7-validator - Using a PHP framework that supports PSR-7? Get free validation without writing a bunch of code, by registering this middleware and pointing it at your API description document.	PHP	❌	✅
openapi_first - It validates requests and responses against your API description using rack middlewares or a low-level interface. It gives you access to request parameters that are parsed exactly as described in your API description and produces useful customizable error responses if request validation fails.	Ruby	❌	✅
Wiremock - WireMock Cloud is a managed, hosted version of WireMock, developed by the same team who wrote the open-source project. It is built on the same technology that powers open source WireMock and is 100% compatible with the WireMock API, with additional features that make it quick and easy to mock any API you depend on. WireMock Cloud also introduces advanced capabilities such as chaos engineering, OpenAPI generation, validation and documentation as well as better collaboration and user management.	SaaS	❌	✅

Documentation

Render API Description as HTML (or maybe a PDF) so slightly less technical people can figure out how to work with the API.

Name	Language	v3.2	v3.1	GitHub
🌿 Fern Sponsored	TypeScript, Java, Python, Go, Ruby, C#, PHP, Swift, and Rust	❌	✅
// Speakeasy - Generate & publish SDKs in 10+ languages, Terraform Providers, and docs from your OpenAPI Sponsored	TypeScript, Python, Go, Java, Terraform, C#, PHP, Ruby, Swift, Unity	✅	✅
Zudoku - OpenAPI powered, highly customizable, API reference and documentation framework with CDN packaged and self-hosted options. Sponsored	TypesScript	❌	✅
openapi-changes - The world's fastest, most beautiful, powerful and detailed OpenAPI change detection tool on earth. Explore every change in An OpenAPI spec. See changes over time, go back into history and see what changed with each commit. Identifies all breaking changes, Powered by libopenapi.	go	✅	✅
Alphadoc - Alphadoc is a full featured developer experience platform. API components with granular parameter control and diagrams generated from your OpenAPI. Not only the reference, but the entire set of tutorials and guides automatically updates when the underlying API updates.	SaaS	❌	✅
api-diff-viewer - React component to view the difference between two Json based API documents. Supported specifications: JsonSchema, OpenAPI 3.x, AsyncAPI 2.x.	TypeScript	❌	✅
API7 Enterprise Edition - A comprehensive API lifecycle management solution based on Apache APISIX, featuring a Developer Portal for onboarding.	Lua	❌	✅
APIdog - A comprehensive, all-in-one API development platform that revolutionizes how teams design, test, and document APIs. Built for modern development workflows, Apidog combines powerful API documentation generation, robust testing capabilities, and intelligent mock servers into a single, intuitive platform.	SaaS	❌	✅
APIGit - the native Git based collaboration platform for API design, document, mock, testing and share.	SaaS	❌	✅
APIMatic Developer Experience Portal - Customizable developer portals packed with language specific documentation, client libraries, code samples, an API console and much more.	SaaS	❌	✅
BlocklyAutomation - Input any OpenAPI document to have generated Blocks in Blockly form to test and generate documentation.	Javascript / .NET	❌	✅
Bump.sh - Bump.sh generates elegant documentation and changelogs from your OpenAPI specifications. Git diff, for your API. Integrates with CI and Slack.	SaaS	❌	✅
DeveloperHub - Collaboration platform for product and API documentation	SaaS	❌	✅
Docuo - Docuo is a lightweight platform that transforms your static contents into a modern developer hub, API reference, product guides, and more.	SaaS	❌	✅
Elements - Build beautiful, interactive API Docs with embeddable React or Web Components, powered by OpenAPI and Markdown	Javascript / Custom Element	❌	✅
Framna Docs - Self-hosted web portal that centralizes OpenAPI documentation and facilitates spec-driven development, built with GitHub-based authorization. Integrates with Swagger UI, Stoplight Elements, and Redocly.	TypeScript	❌	✅
Frevo - Keep track of changes in your OpenAPI specifications & generate API references ⛱️	SaaS	❌	✅
GitBook - Effortlessly publish stunning, interactive documentation for products, APIs, and more.	Web / SaaS	❌	✅
Kong Enterprise Edition - Highly customizable developer portal with developer onboarding, integrated with the Kong API Gateway	Lua	❌	✅
Mintlify - Modern standard for API documentation. Beautiful and easy-to-maintain UI components and interactive playground.	Web / SaaS	❌	✅
MkDocs Redoc Tag - A MkDocs plugin supports adding Redoc to the page.	Python	❌	✅
MkDocs Swagger UI Tag - A MkDocs plugin supports for add Swagger UI in page.	Python	❌	✅
oas_rails - Rails engine for generate automatic interactive documentation in your Rails HTTP APIs.	Ruby	❌	✅
OpenAPI DevTools - Browser extension that generates API specs for any app or website	TypeScript	❌	✅
OpenAPI Explorer - Generate and render fully customizable API documentation, then explore and execute API requests via the integrated console.	Javascript/Custom Element	❌	✅
openapi-dev-tool - OpenAPI Dev Tool proposes to developers a unique tool to address development and industrialization needs!	JavaScript	❌	✅
Openapiviewer - Upload a openapi.json and view it online via a shareable link. Nothing else. Uses OpenAPI Explorer under the hood.	SaaS	❌	✅
RapiDoc - Custom Element to view OpenAPI descriptions.	Web Component	❌	✅
ReadMe - Interactive developer hubs that help users succeed with your APIs 🦉	SaaS	❌	✅
ReDoc - Open source API reference docs from OpenAPI descriptions	React.js	❌	✅
Redocly CLI - Bring versatile OpenAPI validation, linting & bundling to your command line with this open-source Swiss-army knife.	CLI & TypeScript	❌	✅
Restish - A CLI for REST-ish APIs with HTTP/2, built-in auth, content negotiation, caching, and more that understands and can discover OpenAPI descriptions.	CLI / Go	❌	✅
Scalar - Beautiful Open-Source API references from Swagger/OAS files ✨	Vue.js	❌	✅
Scramble - Modern Laravel OpenAPI documentation generator. No PHPDoc annotations required.	PHP	❌	✅
Scribe - Generate API documentation for humans from your Laravel codebase.	PHP	❌	✅
Stoplight Docs - Create beautiful, customizable, interactive API documentation generated from OpenAPI, integrated with Stoplight Studio.	SaaS	❌	✅
Treblle - Treblle is a lightweight SDK that helps Engineering and Product teams build, ship, and maintain REST based APIs faster.		❌	✅
vitepress-openapi - Generate VitePress API Docs from OpenAPI specifications.	Vue, TypeScript	❌	✅
VSCode OpenAPI Preview - Preview OpenAPI v3.0 & v3.1 documents in Visual Studio Code using Spotlight Elements.	TypeScript	❌	✅
VSCode OpenAPI Viewer - Preview and edit JSON or YAML OpenAPI specifications in Visual Studio Code using RapiDoc.	TypeScript	❌	✅
Wiremock - WireMock Cloud is a managed, hosted version of WireMock, developed by the same team who wrote the open-source project. It is built on the same technology that powers open source WireMock and is 100% compatible with the WireMock API, with additional features that make it quick and easy to mock any API you depend on. WireMock Cloud also introduces advanced capabilities such as chaos engineering, OpenAPI generation, validation and documentation as well as better collaboration and user management.	SaaS	❌	✅
xyd - A new scalable docs framework. Generate API Docs from OpenAPI definitions easier. Powered by LiveSession.	TypeScript	❌	✅
Zuplo (OpenAPI-based gateway and documentation) - Zuplo is an API gateway designed for developers. Natively powered by OpenAPI (3.1 or 3.0), zuplo offers an OpenAPI design surface, API documentation and a serverless, programmable edge gateway that includes request validation, auth, rate-limiting and more.	Web / SaaS	❌	✅

DSL

Writing YAML by hand is no fun, and maybe you don't want a GUI, so use a Domain Specific Language to write OpenAPI in your language of choice.

Name	Language	v3.2	v3.1	GitHub
🛠️ Speakeasy OpenAPI - An OSS set of packages and tools used by Speakeasy for working with OpenAPI, Arazzo and Overlay Specification documents. Includes CLI tools for validation, bundling, inlining, upgrading, and more. Sponsored	Go, CLI	✅	✅
OpenAPIKit - Codable Swift types that encode to- and decode from OpenAPI 3.0.x and OpenAPI 3.1.x Documents and their components.	Swift	👷	✅
rswag - Rswag extends rspec-rails request specs with a Swagger-based DSL for describing and testing API operations.	ruby	❌	✅
ts-oas - Automatically generate OpenAPI specifications from lovely Typescript types.	Typescript	❌	✅

Text Editors

Text editors give you visual feedback whilst you write OpenAPI, so you can see what docs might look like.

Name	Language	v3.2	v3.1	GitHub
Fix My OpenAPI - A VSCode Extension by APIMatic - APIMatic's VSCode extension helps you validate, lint, and auto-fix your OpenAPI files, along with other capabilities such as API transformations, API audit report generation, SDKs generation, and more.	Any	❌	✅
Redocly VSCode Extension - Redocly OpenAPI is a Visual Studio Code extension that helps you write, validate, preview, and maintain your OpenAPI documents.	Node.js	❌	✅
SwaggerHub - API design and documentation platform to improve collaboration, standardize development workflow and centralize their API discovery and consumption.	SaaS/On-Premise NodeJS	❌	✅
VSCode OpenAPI Viewer - Preview and edit JSON or YAML OpenAPI specifications in Visual Studio Code using RapiDoc.	TypeScript	❌	✅
Xapi Platform - Xapi is an integrated platform that enables you to implement a streamlined API-first design strategy with standardized API artifacts and collaborative teams.	Saas	❌	✅

GUI Editors

Visual editors help you design APIs without needing to memorize the entire OpenAPI specification.

Name	Language	v3.2	v3.1	GitHub
// Speakeasy - Generate & publish SDKs in 10+ languages, Terraform Providers, and docs from your OpenAPI Sponsored	TypeScript, Python, Go, Java, Terraform, C#, PHP, Ruby, Swift, Unity	✅	✅
Api-Fiddle - Opinionated API design platform built for collaboration and exploration. Create API designs for technical documents, specifications, and reviews.	TypeScript / Saas	❌	✅
APIGit - the native Git based collaboration platform for API design, document, mock, testing and share.	SaaS	❌	✅
DocDriven - DocDriven is a user friendly GUI editor with collaboration features, cloud mock servers and AI code generation.		❌	✅
Flotiq - headless CMS with OpenAPI support - Visually define your Content Types, Flotiq automatically generates your own OpenAPI v3 compatible endpoints, SDKs and Postman collections.	SaaS	❌	✅
Frogment Editor - A free openAPI spec editor and linter that breaks down your spec into fragments to make editing easier and more intuituve.	Desktop / SaaS	❌	✅
Hackolade - A visual editor for OpenAPI v2/v3, from the pioneer in data modeling for NoSQL databases.	ReactJS	❌	✅
OpenAPI Designer - OpenAPI Designer is an easy-to-use, free, web-based, codeless description document editor with JSON and YAML outputs.	SaaS	❌	✅
Stoplight Studio - Stoplight Studio is a powerful GUI/text editor with linting and mocking built right in. The desktop version has been discontinued, but it runs in the browser, powered by your existing GitHub, GitLab, or BitBucket repos.	SaaS	❌	✅
Xapi Platform - Xapi is an integrated platform that enables you to implement a streamlined API-first design strategy with standardized API artifacts and collaborative teams.	Saas	❌	✅
Zuplo (OpenAPI-based gateway and documentation) - Zuplo is an API gateway designed for developers. Natively powered by OpenAPI (3.1 or 3.0), zuplo offers an OpenAPI design surface, API documentation and a serverless, programmable edge gateway that includes request validation, auth, rate-limiting and more.	Web / SaaS	❌	✅

Learning

Whether you're trying to get documentation for a third party API based on traffic, or are trying to switch to design-first at an organization with no OpenAPI at all, learning can help you move your API spec forward and keep it up to date.

Name	Language	v3.2	v3.1	GitHub
// Speakeasy - Generate & publish SDKs in 10+ languages, Terraform Providers, and docs from your OpenAPI Sponsored	TypeScript, Python, Go, Java, Terraform, C#, PHP, Ruby, Swift, Unity	✅	✅
Fitting - Library add improve test log for RSpec and WebMock, validate its according to API Blueprint and Open API, show the documentation coverage with log.	Ruby	❌	✅
InducOapi - A simple python module to generate OpenAPI Description Documents by supplying request/response bodies.	Python	❌	✅
optic - Build your first OpenAPI description from traffic. Use Optic to patch the OpenAPI every time it detects new API behavior.	cli	❌	✅

Mock Servers

Fake servers that take description document as input, then route incoming HTTP requests to example responses or dynamically generates examples.

Name	Language	v3.2	v3.1	GitHub
// Speakeasy - Generate & publish SDKs in 10+ languages, Terraform Providers, and docs from your OpenAPI Sponsored	TypeScript, Python, Go, Java, Terraform, C#, PHP, Ruby, Swift, Unity	✅	✅
APIGit - the native Git based collaboration platform for API design, document, mock, testing and share.	SaaS	❌	✅
Counterfact - Counterfact is a revolutionary free and open source mock server. If you have Node installed, all you have to do is run `npx counterfact@latest path-or-url-to-your-openapi-document`. Out of the box, you'll get a mock server that returns random data. With a TypeScript API that's optimized for mocking, you can add more realistic behavior. It supports mix and matching mocks with calls to the real API (sans CORS headaches). With hot reloading and a REPL, you can change things up on the fly.	TypeScript / Node	❌	✅
DocDriven - DocDriven is a user friendly GUI editor with collaboration features, cloud mock servers and AI code generation.		❌	✅
Microcks - Open source Kubernetes-native tool for API Mocking and Testing. Turn your OAI contract examples into ready-to-use mocks. Use examples to test and validate implementations according to spec and schema elements. Microcks is a Cloud Native Computing Sandbox project 🚀	Java	❌	✅
Mockintosh - Mocks for CloudNative Environments - Converts OpenAPI files to Mocks and use them to develop in isolated environments and test edge cases, Async call to queues such as Kafka or RabbitMQ or simulate performance & chaos testing	CLI / Docker	❌	✅
Mokapi - Mock your APIs – Spin up realistic mocks from OpenAPI, AsyncAPI, LDAP, or SMTP/IMAP files. Extend them with simple JavaScript to simulate real-world scenarios, test microservices, Kafka streams, or email workflows, and integrate seamlessly into CI/CD pipelines. Free, open-source, and fully under your control.	Go	❌	✅
Prism - Turn any OAI file into an API server with mocking, transformations, validations, and more.	cli	❌	✅
Wiremock - WireMock Cloud is a managed, hosted version of WireMock, developed by the same team who wrote the open-source project. It is built on the same technology that powers open source WireMock and is 100% compatible with the WireMock API, with additional features that make it quick and easy to mock any API you depend on. WireMock Cloud also introduces advanced capabilities such as chaos engineering, OpenAPI generation, validation and documentation as well as better collaboration and user management.	SaaS	❌	✅

Description Validators

Check your API description to see if it is valid OpenAPI.

Name	Language	v3.2	v3.1	GitHub
🛠️ Speakeasy OpenAPI - An OSS set of packages and tools used by Speakeasy for working with OpenAPI, Arazzo and Overlay Specification documents. Includes CLI tools for validation, bundling, inlining, upgrading, and more. Sponsored	Go, CLI	✅	✅
OpenAPI::Modern - OpenAPI v3.1, v3.2 validator and JSON Schema validator (drafts 4 through draft2020-12)	Perl	✅	✅
vacuum - A blazing fast OpenAPI linter and validator that is compatible with Spectral rulesets, and designed for enterprise-grade speed and scale.	go	✅	✅
api - Magical SDK generation from an OpenAPI definition	JavaScript, TypeScript	❌	✅
APIMatic OpenAPI Linter - GitHub App - The APIMatic OpenAPI Linter GitHub App automatically validates and lints your OpenAPI definitions within GitHub repositories. Every time you create or update a pull request, the app ensures your API definitions meet high standards for both code generation and documentation generation, helping you maintain consistency and quality across your API projects.	Any	❌	✅
express-openapi-validator - 🦋 Auto-validate API requests and responses in ExpressJS.	JavaScript	❌	✅
Fix My OpenAPI - A VSCode Extension by APIMatic - APIMatic's VSCode extension helps you validate, lint, and auto-fix your OpenAPI files, along with other capabilities such as API transformations, API audit report generation, SDKs generation, and more.	Any	❌	✅
oas-normalize - Comprehensive tooling for working with OpenAPI definitions.	JavaScript, TypeScript	❌	✅
OpenAPI Validator - Configurable and extensible validator/linter for OpenAPI documents	Node.js	❌	✅
openapi-schema-validator - OpenApi description validation	Javascript	❌	✅
openapi-spec-validator - OpenAPI Description validator	Python	❌	✅
openapi-validator-junit - A JUnit extension for validating a wide range of properties of a specification.	Kotlin	❌	✅
OpenAPIKit - Codable Swift types that encode to- and decode from OpenAPI 3.0.x and OpenAPI 3.1.x Documents and their components.	Swift	👷	✅
Rate My OpenAPI - Free and open source OpenAPI automated review and validation tool.	Go	❌	✅
Redocly CLI - Bring versatile OpenAPI validation, linting & bundling to your command line with this open-source Swiss-army knife.	CLI & TypeScript	❌	✅
Spectral - A flexible OpenAPI/AsyncAPI API linter, which can help you build anything from automated API Style Guides for API Governance workflows, or handle any other JSON/YAML object linting. functions.	CLI & TypeScript/JavaScript	❌	✅

Security

By poking around your OpenAPI description, some tools can look out for attack vectors you might not have noticed.

Name	Language	v3.2	v3.1	GitHub
cats - CATS is a REST API Fuzzer and negative testing tool for OpenAPI endpoints. CATS automatically generates, runs and reports tests with minimum configuration and no coding effort. Tests are self-healing and do not require maintenance.	Java	❌	✅
Mayhem for API - Probe your REST API with an infinite stream of test cases generated automatically from your OpenAPI specification.	Any	❌	✅
Rate My OpenAPI - Free and open source OpenAPI automated review and validation tool.	Go	❌	✅
Treblle - Treblle is a lightweight SDK that helps Engineering and Product teams build, ship, and maintain REST based APIs faster.		❌	✅

SDK Generators

Generate code to give to consumers, to help them avoid interacting at a HTTP level.

Name	Language	v3.2	v3.1	GitHub
🌿 Fern - Generate SDKs in popular languages and publish them to package managers (like npm). Sponsored	TypeScript, Java, Python, Go, Ruby, C#, PHP, Swift, and Rust	❌	✅
✨ Stainless - Generate SDKs in popular languages and publish them to package managers (like npm). Sponsored	TypeScript, Python, Go, Java, and Kotlin	❌	✅
// Speakeasy - Generate & publish SDKs in 10+ languages, Terraform Providers, and docs from your OpenAPI Sponsored	TypeScript, Python, Go, Java, Terraform, C#, PHP, Ruby, Swift, Unity	✅	✅
Kiota Api Client Generator - Kiota is a cross platform API Client code generator that is small, fast, and optimized for API consumers to find APIs and generate client code for just the parts of the API that they need. One tool, for any OpenAPI described API, that delivers a consistent client experience in multiple languages.	C#	✅	✅
// SDK-IT - Generates type-safe client SDKs from OpenAPI specifications and creates OpenAPI specs from TypeScript code.	TypeScript, Dart	❌	✅
@hey-api/openapi-ts - The OpenAPI to TypeScript codegen. Generate clients, SDKs, validators, and more.	TypeScript	❌	✅
apigen-ts - Typed HTTP client generator as single file without extra dependencies	TypeScript	❌	✅
APIMatic Generate - Bring in your API description (OAI v2/v3, RAML, API Blueprint, WSDL, etc.) to generate fully functional SDKs in over 10 languages.	SaaS	❌	✅
Ballerina OpenAPI tool - The Ballerina OpenAPI tool enables the generation of Ballerina client and service skeleton from provided OpenAPI descriptions and facilitates the creation of OpenAPI v3.x descriptions for given Ballerina services.	Java, Ballerina	❌	✅
BlocklyAutomation - Input any OpenAPI document to have generated Blocks in Blockly form to test and generate documentation.	Javascript / .NET	❌	✅
Counterfact - Counterfact is a revolutionary free and open source mock server. If you have Node installed, all you have to do is run `npx counterfact@latest path-or-url-to-your-openapi-document`. Out of the box, you'll get a mock server that returns random data. With a TypeScript API that's optimized for mocking, you can add more realistic behavior. It supports mix and matching mocks with calls to the real API (sans CORS headaches). With hot reloading and a REPL, you can change things up on the fly.	TypeScript / Node	❌	✅
docs - A modern alternative to `go-swagger`. Offers generation and parsing of OpenAPI Specs, depending on the usage.		❌	✅
Flotiq - headless CMS with OpenAPI support - Visually define your Content Types, Flotiq automatically generates your own OpenAPI v3 compatible endpoints, SDKs and Postman collections.	SaaS	❌	✅
OpenAPI Commander - Generate a Node.js command line tool from an OpenAPI definition.	Node.js / CLI	❌	✅
OpenAPI JSON Schema Generator - A template-driven engine to generate API client code + documentation by parsing your OpenAPI Description	Python, Java	❌	✅
OpenAPI Qraft - Generate a type-safe TanStack Query client for React from an OpenAPI Document.	TypeScript	❌	✅
openapi-code-generator - A code generation tool for openapi 3 / 3.1, and typespec specifications, primarily aimed at generating typescript client SDKs, and server stubs, with an emphasis on compile & runtime safety.	TypesScript	❌	✅
openapi-ts-sdk-builder - Generate a TypeScript SDK from OpenAPI 3 definitions.	Javascript / TypeScript	❌	✅
OpenApi4s - OpenApi generators for Scala. Direct code generation, minimally intrusive and with automatic refactoring.	Scala	❌	✅
Swift OpenAPI Generator - Generate Swift client and server code from an OpenAPI document. Includes support for type-safe JSON event streaming, multipart, Swift concurrency, customizable middlewares, and pluggable HTTP libraries.	Swift	❌	✅
The Codegen Project - Stop wasting time on manual code. Generate payloads, parameters, headers, types, client wrappers, and more from your OpenAPI document!	TypeScript	❌	✅

Server Implementations

Easily create and implement resources and routes for your APIs.

Name	Language	v3.2	v3.1	GitHub
🌿 Fern - Generate server-side boilerplate code from OpenAPI and then implement your business logic. Sponsored	Express.js, FastAPI, Spring Boot	❌	✅
Mojolicious::Plugin::OpenAPI::Modern - Mojolicious plugin for OpenAPI::Modern	Perl	✅	✅
openapi-processor - Generates java interfaces & DTOs (pojo or record) for Spring Boot (annotation based, MVC & WebFlux) or Micronaut (annotation based) from an OpenAPI YAML/JSON description. Provides powerful type mapping capabilities to adjust the generated code. Gradle & Maven support. Playground.	Java	✅	✅
Ballerina OpenAPI tool - The Ballerina OpenAPI tool enables the generation of Ballerina client and service skeleton from provided OpenAPI descriptions and facilitates the creation of OpenAPI v3.x descriptions for given Ballerina services.	Java, Ballerina	❌	✅
DocDriven - DocDriven is a user friendly GUI editor with collaboration features, cloud mock servers and AI code generation.		❌	✅
express-openapi - An unopinionated OpenAPI framework for Express, which supports Promise based middleware, response handlers and Security Filtering.	Node.js / Typescript	❌	✅
Huma - A modern, simple, fast & flexible micro framework for building HTTP REST/RPC APIs in Go backed by OpenAPI 3 and JSON Schema.	Go	❌	✅
Kappa - Java validation middleware which can be used to validate HTTP requests and responses against OpenAPI 3.1 definitions based on popular but archived openapi4j. Works with Spring and Vert.x.	Java	❌	✅
mondrian-framework - Framework for generating OpenAPI 3.1 documents and servers from formal TypeScript definitions of models and services. Includes built-in data validation.	Typescript	❌	✅
openapi-backend - Build, Validate, Route, and Mock using OpenAPI specification. Framework-agnostic	Node.js + Typescript	❌	✅
openapi-code-generator - A code generation tool for openapi 3 / 3.1, and typespec specifications, primarily aimed at generating typescript client SDKs, and server stubs, with an emphasis on compile & runtime safety.	TypesScript	❌	✅
OpenApi4s - OpenApi generators for Scala. Direct code generation, minimally intrusive and with automatic refactoring.	Scala	❌	✅
Swift OpenAPI Generator - Generate Swift client and server code from an OpenAPI document. Includes support for type-safe JSON event streaming, multipart, Swift concurrency, customizable middlewares, and pluggable HTTP libraries.	Swift	❌	✅
The Codegen Project - Stop wasting time on manual code. Generate payloads, parameters, headers, types, client wrappers, and more from your OpenAPI document!	TypeScript	❌	✅
Whook - OpenAPI 3 based NodeJS server.	Javascript / TypeScript	❌	✅
xyd - A new scalable docs framework. Generate API Docs from OpenAPI definitions easier. Powered by LiveSession.	TypeScript	❌	✅

Miscellaneous

Anything else that does stuff with OpenAPI but hasn't quite got enough to warrant its own category.

Name	Language	v3.2	v3.1	GitHub
// Speakeasy - Generate & publish SDKs in 10+ languages, Terraform Providers, and docs from your OpenAPI Sponsored	TypeScript, Python, Go, Java, Terraform, C#, PHP, Ruby, Swift, Unity	✅	✅
🛠️ Speakeasy OpenAPI - An OSS set of packages and tools used by Speakeasy for working with OpenAPI, Arazzo and Overlay Specification documents. Includes CLI tools for validation, bundling, inlining, upgrading, and more. Sponsored	Go, CLI	✅	✅
openapi-format - A CLI to format an OpenAPI document by ordering fields in a hierarchical order, with the option to filter out flags, tags, methods, operationIDs; including the option to convert between OpenAPI 3.0, 3.1 and 3.2.	Node.js	✅	✅
wiretap - Wiretap is a feature packed OpenAPI compliance testing tool. Validate that a client and server are compliant with an OpenAPI spec. Rewrite paths, inject headers, and even host a UI locally to test an OpenAPI implementation.	go	✅	✅
allof-merge - Simplify your JsonSchema by combining allOf safely	TypeScript	❌	✅
api-diff-viewer - React component to view the difference between two Json based API documents. Supported specifications: JsonSchema, OpenAPI 3.x, AsyncAPI 2.x.	TypeScript	❌	✅
api-ref-bundler - Bundle all external $ref in Json based API document into single document	TypeScript	❌	✅
api-smart-diff - Compare two Json based API documents (OpenAPI, AsyncAPI, JsonSchema, GraphAPI)	TypeScript	❌	✅
express-openapi-validator - 🦋 Auto-validate API requests and responses in ExpressJS.	JavaScript	❌	✅
Flotiq - headless CMS with OpenAPI support - Visually define your Content Types, Flotiq automatically generates your own OpenAPI v3 compatible endpoints, SDKs and Postman collections.	SaaS	❌	✅
Frevo - Keep track of changes in your OpenAPI specifications & generate API references ⛱️	SaaS	❌	✅
go-openapi-spec-code-diffs - A golang validation tool that compares given OpenAPI specs (e.g. openapi.yaml) vis-a-vis routes (e.g. /api/v1/customer/:id) defined in golang source code and reports differences. This is useful in scenarios where you want to keep the OpenAPI specs and Code in synch.	go	❌	✅
oas - Comprehensive tooling for working with OpenAPI definitions	JavaScript, TypeScript	❌	✅
oas-patch - A command-line tool for OpenAPI Overlays, allowing you to patch and modify OpenAPI documents. And create overlays from two openapi documents	Python	❌	✅
OpenAPI CRUD Wizard - This wizard is an IntelliJ Plugin to create a new OpenAPI document including all CRUD operations based only on a Yaml object. No knowledge about OpenAPI specification needed.	Yaml	❌	✅
openapi-dev-tool - OpenAPI Dev Tool proposes to developers a unique tool to address development and industrialization needs!	JavaScript	❌	✅
optic diff - Diff the effective API contract between any two versions of your OpenAPI description. Exit 1 on breaking changes.	Node	❌	✅
Rate My OpenAPI - Free and open source OpenAPI automated review and validation tool.	Go	❌	✅
Restish - A CLI for REST-ish APIs with HTTP/2, built-in auth, content negotiation, caching, and more that understands and can discover OpenAPI descriptions.	CLI / Go	❌	✅
Sourcemeta JSON Schema Standard Library - A growing collection of battle-tested schemas (ISO, IETF, IEC, W3C, etc) to power your next API spec, so you never have to bother with JSON Schema again	JSON	❌	✅
The Codegen Project - Stop wasting time on manual code. Generate payloads, parameters, headers, types, client wrappers, and more from your OpenAPI document!	TypeScript	❌	✅
Treblle - Treblle is a lightweight SDK that helps Engineering and Product teams build, ship, and maintain REST based APIs faster.		❌	✅

Parsers

Loads and read OpenAPI descriptions, so you can work with them programmatically.

Name	Language	v3.2	v3.1	GitHub
🛠️ Speakeasy OpenAPI - An OSS set of packages and tools used by Speakeasy for working with OpenAPI, Arazzo and Overlay Specification documents. Includes CLI tools for validation, bundling, inlining, upgrading, and more. Sponsored	Go, CLI	✅	✅
libopenapi - Enterprise grade, fully featured OpenAPI 3.1, 3.0 and Swagger parser library for go. A complete toolset for reading and parsing OpenAPI and Swagger specifications. Comes complete with high and low-level APIs, diff engine, index and resolver.	go	✅	✅
Microsoft/OpenAPI.NET - C# based parser with OpenAPI Description validation and migration support from V2	.NET	✅	✅
openapi-format - A CLI to format an OpenAPI document by ordering fields in a hierarchical order, with the option to filter out flags, tags, methods, operationIDs; including the option to convert between OpenAPI 3.0, 3.1 and 3.2.	Node.js	✅	✅
openapi-processor/openapi-parser - OpenAPI parser with (JSON schema) validation. Separate APIs for OpenAPI 3.2, 3.1, 3.0. Easily get resolved $ref objects. Pluggable document reader & JSON/YAML converter. Minimal dependencies.	Java	✅	✅
api - Magical SDK generation from an OpenAPI definition	JavaScript, TypeScript	❌	✅
oas-normalize - Comprehensive tooling for working with OpenAPI definitions.	JavaScript, TypeScript	❌	✅
OpenAPIKit - Codable Swift types that encode to- and decode from OpenAPI 3.0.x and OpenAPI 3.1.x Documents and their components.	Swift	👷	✅
swagger-parser - Swagger Parser reads OpenAPI definitions into current Java POJOs.	Java	❌	✅

Testing

Quickly execute API requests and validate responses on the fly through command line or GUI interfaces.

Name	Language	v3.2	v3.1	GitHub
// Speakeasy - Generate & publish SDKs in 10+ languages, Terraform Providers, and docs from your OpenAPI Sponsored	TypeScript, Python, Go, Java, Terraform, C#, PHP, Ruby, Swift, Unity	✅	✅
openapi-changes - The world's fastest, most beautiful, powerful and detailed OpenAPI change detection tool on earth. Explore every change in An OpenAPI spec. See changes over time, go back into history and see what changed with each commit. Identifies all breaking changes, Powered by libopenapi.	go	✅	✅
wiretap - Wiretap is a feature packed OpenAPI compliance testing tool. Validate that a client and server are compliant with an OpenAPI spec. Rewrite paths, inject headers, and even host a UI locally to test an OpenAPI implementation.	go	✅	✅
APIdog - A comprehensive, all-in-one API development platform that revolutionizes how teams design, test, and document APIs. Built for modern development workflows, Apidog combines powerful API documentation generation, robust testing capabilities, and intelligent mock servers into a single, intuitive platform.	SaaS	❌	✅
APIGit - the native Git based collaboration platform for API design, document, mock, testing and share.	SaaS	❌	✅
BlocklyAutomation - Input any OpenAPI document to have generated Blocks in Blockly form to test and generate documentation.	Javascript / .NET	❌	✅
Fitting - Library add improve test log for RSpec and WebMock, validate its according to API Blueprint and Open API, show the documentation coverage with log.	Ruby	❌	✅
Mayhem for API - Probe your REST API with an infinite stream of test cases generated automatically from your OpenAPI specification.	Any	❌	✅
Microcks - Open source Kubernetes-native tool for API Mocking and Testing. Turn your OAI contract examples into ready-to-use mocks. Use examples to test and validate implementations according to spec and schema elements. Microcks is a Cloud Native Computing Sandbox project 🚀	Java	❌	✅
openapi-dev-tool - OpenAPI Dev Tool proposes to developers a unique tool to address development and industrialization needs!	JavaScript	❌	✅
portman - Port OpenAPI Spec to Postman Collection, with contract & variation tests included!	Node.js	❌	✅
Restish - A CLI for REST-ish APIs with HTTP/2, built-in auth, content negotiation, caching, and more that understands and can discover OpenAPI descriptions.	CLI / Go	❌	✅
Spectator - Spectator provides light-weight OpenAPI testing tools you can use within your existing Laravel test suite.	PHP	❌	✅
swagger-coverage-cli - A Node.js CLI tool to measure test coverage of Swagger/OpenAPI specs using Postman collections or Newman run reports. Features smart endpoint mapping with intelligent status code prioritization and enhanced path matching.	Node.js	❌	✅
The Codegen Project - Stop wasting time on manual code. Generate payloads, parameters, headers, types, client wrappers, and more from your OpenAPI document!	TypeScript	❌	✅
Wiremock - WireMock Cloud is a managed, hosted version of WireMock, developed by the same team who wrote the open-source project. It is built on the same technology that powers open source WireMock and is 100% compatible with the WireMock API, with additional features that make it quick and easy to mock any API you depend on. WireMock Cloud also introduces advanced capabilities such as chaos engineering, OpenAPI generation, validation and documentation as well as better collaboration and user management.	SaaS	❌	✅
Xapi Platform - Xapi is an integrated platform that enables you to implement a streamlined API-first design strategy with standardized API artifacts and collaborative teams.	Saas	❌	✅

Gateways

API Gateways and related tools that have integrated support for OpenAPI.

Name	Language	v3.2	v3.1	GitHub
Membrane API Gateway - Open source API gateway with built-in OpenAPI support. Turn OpenAPI specs into APIs and enforce request and response validation.	Java	✅	✅
wiretap - Wiretap is a feature packed OpenAPI compliance testing tool. Validate that a client and server are compliant with an OpenAPI spec. Rewrite paths, inject headers, and even host a UI locally to test an OpenAPI implementation.	go	✅	✅
Apache APISIX - APISIX API Gateway offers a variety of traffic management features, including load balancing, dynamic upstream, canary release, circuit breaking, authentication, observability, and more.	Lua	❌	✅
API7 Enterprise Edition - A comprehensive API lifecycle management solution based on Apache APISIX, featuring a Developer Portal for onboarding.	Lua	❌	✅
Kong Enterprise Edition - Highly customizable developer portal with developer onboarding, integrated with the Kong API Gateway	Lua	❌	✅
Serverless API Gateway - Serverless API Gateway is a serverless, open-source, and free API Gateway that is designed to be used with any HTTP source.	TypeScript	❌	✅
Zuplo (OpenAPI-based gateway and documentation) - Zuplo is an API gateway designed for developers. Natively powered by OpenAPI (3.1 or 3.0), zuplo offers an OpenAPI design surface, API documentation and a serverless, programmable edge gateway that includes request validation, auth, rate-limiting and more.	Web / SaaS	❌	✅

Monitoring

Monitoring tools let you know what is going on in your API.

Name	Language	v3.2	v3.1	GitHub
APIdog - A comprehensive, all-in-one API development platform that revolutionizes how teams design, test, and document APIs. Built for modern development workflows, Apidog combines powerful API documentation generation, robust testing capabilities, and intelligent mock servers into a single, intuitive platform.	SaaS	❌	✅
Apitally - Simple REST API monitoring tool that helps engineering and product teams understand their APIs. Tracks usage, errors, response times and more using middleware for Python and Node.js frameworks. Also offers uptime monitoring and logging of individual requests.	SaaS	❌	✅
Treblle - Treblle is a lightweight SDK that helps Engineering and Product teams build, ship, and maintain REST based APIs faster.		❌	✅