Rest Api Design Tool Free

OpenAPI.Tools

We want to keep API developers up to date with the best OpenAPI tooling around, and help direct folks to high quality modern tooling, instead of being stuck on old v2-based rubbish.

Contribute APIs You Won't Hate

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.
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.
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	v3.1	v3.0	v2.0	GitHub
har2openapi - Automatically generate OpenAPI 3.0 Spec by using network requests captured in one or more HAR files	TypeScript	❌	✅	❌

Converters

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

Name	Language	v3.1	v3.0	v2.0
Apimatic Transformer - Transform API Descriptions to and from RAML, API Blueprint, OAI v2/v3, WSDL, etc.	SaaS	✅	✅	✅
avantation - Generate OpenAPI 3.x specification from HAR.	TypeScript	❌	✅	❌
go-swagger - Unmaintained v2.0 only project seeking new maintainer, or probably a fork. Parser, validator, generates descriptions from code, or code from descriptions!	Go	❌	❌	✅
Google Gnostic - Compile OpenAPI descriptions into equivalent Protocol Buffer representations	Go	❌	✅	✅
JSON Schema to OpenAPI Schema - Due to the OpenAPI v3.0 and JSON Schema discrepancy, you can use this JS library to convert JSON Schema objects to OpenAPI Schema.	JavaScript	❌	✅	❌
laravel-openapi - Generate OpenAPI 3 specification for Laravel Applications.	PHP	❌	✅	❌
OAS RAML Converter - Converts between OpenAPI and RAML API specifications	Node.js	❌	✅	✅
OData OpenAPI - OData 4.0, 3.0, and 2.0 to OpenAPI v3.0 and v2.0 converter	Node.js / XSLT	❌	✅	✅
OData.OpenAPI - Convert an Edm (Entity Data Model) to OpenAPI 3.0	.NET	❌	✅	❌
odata2openapi - OData 4.0 to OpenAPI v2.0 converter	Node.js	❌	❌	✅
OpenAPI Filter - Filter internal components from OpenAPI Descriptions	Node.js	❌	✅	✅
OpenAPI Schema to JSON Schema - Due to the OpenAPI v3.0 and JSON Schema discrepancy, you can use this JS library to convert OpenAPI Schema objects to proper JSON Schema.	JavaScript	❌	✅	❌
openapi-python-client - Generate modern Python clients from OpenAPI 3.0 documents.	Python	❌	✅	❌
openapi-to-postman - Convert OpenAPI 3.0 specs to the Postman Collection (v2) format	JavaScript	❌	✅	❌
portman - Port OpenAPI Spec to Postman Collection, with contract & variation tests included!	Node.js	❌	✅	❌
pyswagger - Client & converter in Python, which is type-safe, dynamic, spec-compliant.	Python	❌	❌	✅
swagger2openapi - Upgrade files from OpenAPI v2.0 to v3.0, bundling into one mega file or respecting $refs. Part of oas-kit.	Node.js / CLI	❌	✅	✅

Data Validators

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

Name	Language	v3.1	v3.0	v2.0
APIFuzzer - Fuzz test your application using your OpenAPI definition without coding. Integrate into CI/CD, get Junit XML test result and JSON report of failures	Python	❌	✅	✅
committee - Validation middleware for Rack server. This gem validates request and response using an OpenAPI Description. And convert parameter string to specific Ruby object (e.g. convert datetime string to DateTime class).	Ruby	❌	✅	✅
express-openapi-validator - 🦋 Auto-validate API requests and responses in ExpressJS.	JavaScript	❌	✅	❌
JSONSchema::Validator - A Perl library which validates request/response according to an OpenAPI specification	Perl	❌	✅	❌
kin-openapi - A Go library for handling OpenAPI 3.0 specifications	Go	❌	✅	❌
oas-tools - NodeJS module to manage RESTful APIs defined with OpenAPI 3.0 Description over express servers, including security validations	Node.js	❌	✅	❌
OpenAPI Enforcer - Validate your OpenAPI document, serialize, deserialize, and validate incoming requests and outgoing responses, and simplify response building. You can even produce mock data.	Node.js	❌	✅	✅
OpenAPI HttpFoundation Testing - Strengthen your API tests by validating HttpFoundation responses 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-examples-validator - Validates embedded JSON-examples in OpenAPI-specs	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-spring-webflux-validator - 🌱 A friendly kotlin library to validate API endpoints using an OpenAPI 3.0 or OpenAPI 2.0 specification	Java/Kotlin	❌	✅	✅
openapi-validator-bundle - Validates Request and Response using Symfony Framework	PHP	❌	✅	❌
openapi-validator-middleware - Express middleware which validates request body, headers, path parameters and query parameters according to an OpenAPI Description	Node.js	❌	✅	✅
OpenAPI3 Fuzzer - Simple fuzzer for OpenAPI 3 specification based APIs. Verifies responses and sends various attack patterns.	Python	❌	✅	❌
openapi4j - Parse Description Document, validate API requests and responses using OpenAPI 3.x.	Java	❌	✅	❌
openVALIDATION - Allows complex validation rules to be specified in openAPI spec files using natural language.	Java	❌	✅	❌

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	v3.1	v3.0	v2.0
APIMatic Developer Experience Portal - Customizable developer portals packed with language specific documentation, client libraries, code samples, an API console and much more.	SaaS	✅	✅	✅
Apitive Studio - A platform for Digital Product Managers and API Consultants to design REST APIs with in-built mock and documentation.	Angular 7.0, Java / Saas	❌	✅	✅
APITree - HUB for managing and sharing APIs. Converts OpenAPI v2 / v3 files into beautiful API documentation.	SaaS	❌	✅	✅
Bump - Bump generates elegant documentation and changelogs from your OpenAPI specifications. Git diff, for your API.	SaaS	❌	✅	✅
DeveloperHub - Collaboration platform for product and API documentation	SaaS	✅	✅	✅
Elements - Build beautiful, interactive API Docs with embeddable React or Web Components, powered by OpenAPI and Markdown	Javascript / Custom Element	✅	✅	✅
jekyll-openapi - An OpenAPI 3 documentation website generator built with Jekyll for use on GitHub Pages.	Jekyll	❌	✅	❌
Kong Enterprise Edition - Highly customizable developer portal with developer onboarding, integrated with the Kong API Gateway	Lua	❌	✅	✅
LucyBot DocGen - Generate a customizable website, with API documentation, console, and interactive workflows, from an OpenAPI spec	JavaScript	❌	✅	✅
MrinDoc - OpenAPI description document viewer.	Vue.JS	❌	✅	✅
Nexmo OAS Renderer - Ruby OpenAPI docs rendering, use standalone or add to your Rails app	Ruby	❌	✅	❌
oas-tools - NodeJS module to manage RESTful APIs defined with OpenAPI 3.0 Description over express servers, including security validations	Node.js	❌	✅	❌
oas3-api-snippet-enricher - Enrich your existing description documents with generated code samples	JavaScript	❌	✅	❌
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	❌	✅	❌
openapi-viewer - Browse and test a REST API described with the OpenAPI 3.0 Specification	Vue.js	❌	✅	❌
OpenDocumenter - OpenDocumenter is a automatic documentation generator for OpenAPI v3 schemas. Simply provide your schema file in JSON or YAML, then sit back and enjoy the documentation.	Vue.js	❌	✅	✅
RapiDoc - Custom Element to view OpenAPI descriptions.	Custom Element	✅	✅	✅
RapiPdf - Custom Element to generate PDF from OpenAPI descriptions.	Custom Element	❌	✅	✅
ReadMe - Build beautiful, personalized, interactive developer hubs	SaaS	❌	✅	✅
ReDoc - OpenAPI-generated API Reference Documentation	React.js	✅	✅	✅
RestCase Docs - An API-first and security-first management platform. Design visually and we will create a beautiful API documentation for your APIs.	SaaS	❌	✅	✅
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	❌	✅	❌
Stoplight Docs - Create beautiful, customizable, interactive API documentation generated from OpenAPI, integrated with Stoplight Studio.	SaaS	✅	✅	✅
widdershins - Generate Slate/Shins markdown from OpenAPI 2.0/3.0.x	Node.js	❌	✅	✅

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	v3.1	v3.0	v2.0
BOATS - BOATS allows for larger teams to contribute to multi-file OpenAPI definitions by writing Nunjucks tpl syntax in yaml with a few important helpers to ensure stricter consistency, eg operationId: <$ uniqueOpId() $>.	Node.js	❌	✅	✅
CUE - CUE is an open source language, with a rich set of APIs and tooling, for defining, generating, and validating all kinds of data configuration, APIs, database schemas, code, etc. CUE currently supports generating OpenAPI through its API.	CUE	❌	✅	❌
Goa - Goa provides a holistic approach for developing remote APIs and microservices in Go. implementers don't have to worry about the documentation getting out of sync as Goa takes care of generating OpenAPI specifications for HTTP based services and gRPC protocol buffer files for gRPC based services	Go	❌	✅	✅
Spot - A concise, developer-friendly way to describe your API contract.	TypeScript	❌	✅	✅
Supermodel - Model your data using JSON Schema, refer and remix the models freely, convert to various formats including OAS v2/v3.	SaaS	❌	✅	✅

Text Editors

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

Name	Language	v3.1	v3.0	v2.0
Atom/linter-openapi - This plugin for Atom Linter will lint OpenAPI YAML files using openapi-enforcer node package.	JavaScript	❌	✅	❌
Atom/linter-swagger - This plugin for Atom Linter will lint OpenAPI, both JSON and YAML using swagger-parser node package.	JavaScript	❌	✅	✅
KaiZen-OpenAPI-Editor - Full-featured Eclipse editor for OpenAPI, also available on Eclipse Marketplace.	Java	❌	✅	✅
Senya Editor - JetBrains IDE plugin to show Swagger UI as a preview, for visual feedback as you edit.	Java	❌	✅	✅
Swagger Editor - Design, describe, and document your API on the first open source editor fully dedicated to OpenAPI-based APIs.	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 - OpenAPI extension for Visual Studio Code - new file templates, navigation, intellisense, code snippets.	Any	❌	✅	✅
VSCode OpenAPI Snippets - OpenAPI Snippets for Visual Studio Code editor, includes split file validation	Any	❌	✅	❌
VSCode/openapi-lint - OpenAPI 2.0/3.0.x intellisense, validator and linter for Visual Studio Code	Node.js	❌	✅	✅

GUI Editors

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

Name	Language	v3.1	v3.0	v2.0
ApiBldr - Web-Based API Designer for OpenAPI (swagger) and AsyncAPI specifications.	Angular 9.0 / Saas	❌	✅	✅
Apicurio Studio - Web-Based Open Source API Design via the OpenAPI specification.	Angular 7.0, Java / Saas	❌	✅	✅
Apitive Studio - A platform for Digital Product Managers and API Consultants to design REST APIs with in-built mock and documentation.	Angular 7.0, Java / Saas	❌	✅	✅
Flotiq - headless CMS with OpenAPI support - Visually define your Content Types, Flotiq automatically generates your own OpenAPI v3 compatible endpoints, SDKs and Postman collections.		❌	✅	❌
Hackolade - A visual editor for OpenAPI v2/v3, from the pioneer in data modeling for NoSQL databases.	ReactJS	❌	✅	✅
JSON Designer - Visualize JSON models from imported OpenAPI YAML. Edit models and export OpenAPI YAML.	iOS/Swift	❌	✅	❌
OAIE Sketch - Browser based OpenApi Integrated Editor with side-by side view of the yaml and an interactive graph.	Vue.js	❌	✅	❌
RepreZen API Studio - RepreZen API Studio is an integrated workbench that brings API-first design into focus for your whole team, harmonizes your API designs, and generates APIs that click into client apps.	Java	❌	✅	✅
RestCase Designer - A design-first API managment platform with WYSIWYG API Designer for OpenAPI and AsyncAPI specifications.	Angular 9.0 / Saas	❌	✅	✅
Stoplight Studio - Stoplight Studio is a GUI/text editor with linting and mocking built right in. It can run on the desktop with local files, and in the browser powered by your existing GitHub, GitLab, or BitBucket repos.	Desktop / SaaS	✅	✅	✅

Mock Servers

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

Name	Language	v3.1	v3.0	v2.0
API Sprout - Lightweight, blazing fast, cross-platform OpenAPI 3 mock server with validation	cli / Docker	❌	✅	❌
Apitive Studio - A platform for Digital Product Managers and API Consultants to design REST APIs with in-built mock and documentation.	Angular 7.0, Java / Saas	❌	✅	✅
Connexion - OpenAPI First framework for Python on top of Flask with automatic endpoint validation & OAuth2 support	Python	❌	✅	✅
Fakeit - Create mock server from OpenAPI 3 specification with random response generation and request validation.	cli / Docker	❌	✅	❌
Falcon Heavy - The framework for building app backends and microservices via the API design-first workflow.	Python	❌	✅	❌
Meeshkan - Mock HTTP APIs through a combination of API definitions, recorded traffic and code. Used for sandboxes, as well as automated and exploratory testing.	Python	❌	✅	❌
Microcks - 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 spec and schema elements.	Self-hosted / SaaS	✅	✅	✅
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	✅	✅	✅
MockLab - SaaS platform to upload your spec to create a mock server	SaaS	❌	✅	✅
OpenAPI Mocker - Standalone nodejs based OpenAPI 3 mock server, docker-friendly with request validation and autoreload.	nodejs	❌	✅	❌
openapi-data-mocker - Tiny library to generate basic OpenAPI Data Types. Consider it as extended Faker package. First version able to mock most of the data formats. It doesn't support polymorphism yet, but work in progress. May be useful for writing custom unit tests.	PHP	❌	✅	❌
Prism - Turn any OAI file into an API server with mocking, transformations, validations, and more.	cli	✅	✅	✅
Sandbox - SaaS, self-hosted, or CLI tool for turning OpenAPI (and other) descriptions into a mock server, where you can modify behaviour, simulate downtime, and any other nonsense you can think of thanks to a built-in code editor!	SaaS / Java	❌	✅	✅
Unmock - API integration testing library that intercepts outgoing requests and serves back mock data based on the OpenAPI descriptions.	Node.js	❌	✅	❌
yii2-app-api - Generate Server side API code with routing, models, data validation and database schema from an OpenAPI description. Based on Yii Framework.	PHP	❌	✅	❌

SDK Generators

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

Name	Language	v3.1	v3.0	v2.0
APIMatic CodeGen - Bring in your API description (OAI v2/v3, RAML, API Blueprint, WSDL, etc.) to generate fully functional SDKs in over 10 languages.	SaaS	✅	✅	✅
Flotiq - headless CMS with OpenAPI support - Visually define your Content Types, Flotiq automatically generates your own OpenAPI v3 compatible endpoints, SDKs and Postman collections.		❌	✅	❌
go-swagger - Unmaintained v2.0 only project seeking new maintainer, or probably a fork. Parser, validator, generates descriptions from code, or code from descriptions!	Go	❌	❌	✅
guardrail - Principled code generation from OpenAPI descriptions	Scala, Java, ...	❌	✅	✅
janephp/open-api - Generate a PHP Client API (PSR-7 compatible) given a OpenAPI specification.	PHP	❌	✅	✅
oa-client - Flexible client helper for making and validating calls to OpenAPI backends. For Node and the browser. Runtime lib - no need for code generation!	TypeScript	❌	✅	❌
oazapfts! - Generate TypeScript clients from a given OpenAPI description document.	TypeScript	❌	✅	✅
OpenAPI Client Generators - .NET Core command line program to generate strongly typed client API codes in C# on .NET Frameworks and .NET Core, and in TypeScript for Angular 5+, Aurelia, jQuery, AXIOS and Fetch API.	C#	❌	✅	✅
OpenAPI Generator - A template-driven engine to generate documentation, API clients and server stubs in different languages by parsing your OpenAPI Description (community-driven fork of swagger-codegen)	Java	❌	✅	✅
restful-react - Generate React hooks with appropriate type-signatures from OpenAPI descriptions	React (Typescript)	❌	✅	✅
Unchase.OpenAPI.Connectedservice - Visual Studio extension to generate C# (TypeScript) HttpClient (or C# Controllers) code for OpenAPI web service with NSwag.	.NET	❌	✅	✅

Server Implementations

Easily create and implement resources and routes for your APIs.

Name	Language	v3.1	v3.0	v2.0
@eropple/nestjs-openapi3 - Integrates tightly with a NestJS application to infers complex descriptions and expresses them in its generated OpenAPI document. It then presents that document via ReDoc, and validates inputs for conformance to spec.	Node.js	❌	✅	❌
@nestjs/swagger - Official OpenAPI (Swagger) module for NestJS. Use decorators to define OpenAPI endpoint documentation, parameters and return types. Integrates tightly with a NestJS application. Ships with Swagger UI and serves OpenAPI v3 spec.	TypeScript	❌	✅	❌
@smartrecruiters/openapi-first - Initializes your API express application with the description in OpenAPI 3.0 format using provided middlewares (parsers, validators, controller, defaults setting) or custom ones	Node.js	❌	✅	❌
API Platform - REST and GraphQL framework to build modern API-driven projects	PHP	❌	✅	✅
BaucisJS + baucis-openapi3 - Create REST resources with persistence on MongoDB and expose OpenAPI v.3 contracts	JavaScript	❌	✅	❌
Falcon Heavy - The framework for building app backends and microservices via the API design-first workflow.	Python	❌	✅	❌
Fusio - Open source API management platform	PHP	❌	✅	❌
LoopBack 4 - A highly extensible object-oriented Node.js and TypeScript framework for building APIs and microservices with tight OpenAPI 3 integration. Serves Swagger UI and OpenAPI 3 spec out of the box. Generate code to interact with other OpenAPI-compliant APIs, or generate new API endpoints based on existing OpenAPI specs.	TypeScript	❌	❌	❌
MicroTS - Take an OpenAPI description and generate TypeScript projects via Docker.	Node.js	❌	✅	✅
Mojolicious::Plugin::OpenApi - Mojolicious::Plugin::OpenAPI is a plugin for Mojolicious framework that add routes and input/output validation to your Mojolicious application based on OpenAPI description documents.'	Perl	❌	✅	✅
oas-tools - NodeJS module to manage RESTful APIs defined with OpenAPI 3.0 Description over express servers, including security validations	Node.js	❌	✅	❌
OpenAPI Enforcer Middleware - An express middleware that makes it easy to write web services that follow an OpenAPI specification by leveraging the tools provided in the openapi-enforcer package.	Node.js	❌	✅	✅
openapi-backend - Build, Validate, Route, and Mock using OpenAPI specification. Framework-agnostic	Node.js	✅	✅	❌
openapi-processor-spring - Generates java interfaces & model classes for Spring Boot (annotation based, MVC & WebFlux) from an openapi.yaml. Provides type mapping capabilities to adjust the generated code. Gradle support.	Java	❌	✅	❌
SpringFox - Automated JSON API documentation for API's built with Spring and SpringBoot	Java, Kotlin, Groovy, Ruby	❌	✅	✅
tsoa - Creates OpenAPI docs and provides free runtime validation for your Koa, Express, Hapi (and more) services	TypeScript	❌	✅	✅
Vert.x Web Api Contract - Create API endpoints with Vert.x 3 and OpenAPI 3 with automatic requests validation	Java, Kotlin, JavaScript, Groovy, Ruby, Ceylon & Scala	❌	✅	❌
Vert.x Web API Service - Create API service proxies using event bus with request/response validation	Java	❌	✅	❌
yii2-app-api - Generate Server side API code with routing, models, data validation and database schema from an OpenAPI description. Based on Yii Framework.	PHP	❌	✅	❌

Miscellaneous

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

Name	Language	v3.1	v3.0	v2.0
$ oas (CLI) - Generate OAS files from code comments and easily host them ($ npm install oas -g)	JavaScript	❌	✅	✅
@redocly/openapi-cli - OpenAPI 3 CLI toolbox with rich validation and bundling features.	CLI & TypeScript/JavaScript	✅	✅	✅
Django REST Framework - Automates generation of OpenAPI 3 description documents either as a static file (via CLI command) or a dynamic view within the Django REST Framework (DRF) application.	Python	❌	✅	❌
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.		❌	✅	❌
laravel-openapi - Generate OpenAPI 3 specification for Laravel Applications.	PHP	❌	✅	❌
oa-client - Flexible client helper for making and validating calls to OpenAPI backends. For Node and the browser. Runtime lib - no need for code generation!	TypeScript	❌	✅	❌
oasdiff - Golang module for deep comparison of two OpenAPI specifications. Available also as a command-line.	Go	✅	✅	❌
OAuth2 as OpenAPI Spec 3.0 components - OAuth2 token endpoint described with OAS3 schema. All grants documented. Can be installed as NPM or Composer package.	Any	❌	✅	❌
OpenAPI Server Code Generator (oapi-codegen) - Generate a web service using the [Echo](https://github.com/labstack/echo) framework from an OpenAPI v3 specification	Go	❌	✅	❌
openapi-cli-tool - Can list up defined API paths and bundle multi-file into one. Supports multiple file extensions.	Python	❌	✅	❌
openapi-dev-tool - OpenAPI Dev Tool proposes to developers a unique tool to address development and industrialization needs!	JavaScript	❌	✅	❌
openapi-diff - Utility for comparing two OpenAPI specifications.	Java	❌	✅	❌
openapi-examples-validator - Validates embedded JSON-examples in OpenAPI-specs	JavaScript	❌	✅	✅
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	Node.js	❌	✅	❌
openapi-spring-webflux-validator - 🌱 A friendly kotlin library to validate API endpoints using an OpenAPI 3.0 or OpenAPI 2.0 specification	Java/Kotlin	❌	✅	✅
openVALIDATION - Allows complex validation rules to be specified in openAPI spec files using natural language.	Java	❌	✅	❌
php-openapi-faker - Library to generate fake data for OpenAPI 3.x requests, responses and schemas.	PHP	❌	✅	❌
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	❌	✅	❌

Parsers

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

Name	Language	v3.1	v3.0	v2.0
BigstickCarpet/swagger-parser - Swagger/OpenAPI 2.0 and 3.0 parser and validator. Can also bundle multiple files into one via `$ref`.	Node.js	❌	✅	✅
KaiZen OpenAPI Parser - High-performance Parser, Validator, and Java Object Model for OpenAPI 3.x	Java	❌	✅	❌
kin-openapi - A Go library for handling OpenAPI 3.0 specifications	Go	❌	✅	❌
Microsoft/OpenAPI.NET - C# based parser with OpenAPI Description validation and migration support from V2	.NET	❌	✅	✅
oas-tools - NodeJS module to manage RESTful APIs defined with OpenAPI 3.0 Description over express servers, including security validations	Node.js	❌	✅	❌
oas_parser - A Ruby parser for OpenAPI 3.0+ descriptions.	Ruby	❌	✅	❌
Object Oriented OpenAPI Specification - An object oriented approach to generating OpenAPI Descriptions, implemented in PHP	PHP	❌	✅	❌
openapi-filter - OpenAPI 2.0 and 3.0 filter utility. A CLI/module to filter out internal/private paths, operations, parameters, schemas etc from OpenAPI v1/OpenAPI v2/AsyncAPI definitions. Simply flag any OpenAPI object within the definition with an `x-internal` specification extension or target a OpenAPI property (tags, methods, OperationId), and it will be removed from the output.	Node.js	❌	✅	✅
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	Node.js	❌	✅	❌
openapi-snippet - Generates code snippets in various languages & tools (cURL, Node, Python, Ruby, Java, Go, C#...), from OpenAPI documents.	Node.js	❌	✅	✅
openapi-snippet-cli - Adds code snippets in redoc style (x-codeSamples) to OpenAPI documents. This is a CLI wrapper for the "openapi-snippet".	Node.js	❌	✅	✅
OpenAPI-TS - TS Model & utils for OpenAPI 3.0.x contracts	TypeScript	❌	✅	❌
openapi3 - An OpenAPI 3 Specification client, and validator, covering both description validation and limited data validation for Python 3.	Python	❌	✅	❌
OpenAPI3-Rust - Rust serialization library for OpenAPI v3	Rust	❌	✅	❌
openapi3_parser - A Ruby implementation of parser and validator for the OpenAPI 3 Specification.	Ruby	❌	✅	❌
openapi4j - Parse Description Document, validate API requests and responses using OpenAPI 3.x.	Java	❌	✅	❌
php-openapi - A PHP library for manipulating and validating OpenAPI 3.0 Descriptions	PHP	❌	✅	❌
psx-api - Parse and generate API specification formats	PHP	❌	✅	✅
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	v3.1	v3.0	v2.0
Assertible - Import an OpenAPI specification into Assertible to generate tests that validate JSON Schema responses and status codes on every endpoint.	SaaS	❌	✅	✅
Chai OpenAPI Response Validator - Simple Chai support for asserting that HTTP responses satisfy an OpenAPI spec.	Node.js	❌	✅	✅
Dredd - Language-agnostic command-line tool for validating API description document against backend implementation of the API	Javascript	❌	✅	✅
EvoMaster - A tool for automatically generating system-level test cases for RESTful APIs, using Evolutionary Algorithms and Dynamic Program Analysis.	Java/Kotlin	❌	✅	✅
hikaku - A library that tests if the implementation of a REST-API meets its specification.	Kotlin	❌	✅	❌
jest-openapi - Additional Jest matchers for asserting that HTTP responses satisfy an OpenAPI spec.	Node.js	❌	✅	✅
Mayhem for API - Probe your REST API with an infinite stream of test cases generated automatically from your OpenAPI specification.	Any	❌	✅	✅
Microcks - 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 spec and schema elements.	Self-hosted / SaaS	✅	✅	✅
OpenAPI Enforcer - Validate your OpenAPI document, serialize, deserialize, and validate incoming requests and outgoing responses, and simplify response building. You can even produce mock data.	Node.js	❌	✅	✅
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	❌	✅	❌
ReadyAPI - an end to end API functional, security, performance and virtualization tool where OAS description documents can be utilized to automate the creation and validation of end to end tests, running them manually or at any point in your CI/CD pipeline. pipelines.	Java	❌	✅	✅
RESTest - RESTest is a framework for automated black-box testing of RESTful web APIs. It follows a model-based approach, where test cases are automatically derived from the OpenAPI description document (OAS) of the API under test.	Java	❌	✅	✅
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	❌	✅	❌
Schemathesis - Reads the description document and generates test cases that will ensure that your application is compliant with its description.	Python	❌	✅	✅
Spectator - Spectator provides light-weight OpenAPI testing tools you can use within your existing Laravel test suite.	PHP	❌	✅	❌
Swagger Inspector - Swagger Inspector is a free online tool to quickly execute any API request, validate its responses and generate a corresponding OpenAPI Description.	Self-hosted/SaaS	❌	✅	✅
Tcases for OpenAPI - Generates test cases directly from an OpenAPI v3 description of your API. Creates tests executable using various test frameworks. Bonus: Semantic linter reports elements that are inconsistent, superfluous, or dubious.	Java	❌	✅	❌
Unmock - API integration testing library that intercepts outgoing requests and serves back mock data based on the OpenAPI descriptions.	Node.js	❌	✅	❌
vREST NG - vREST NG is a simple and powerful application for API Automation. It Allows to use OpenAPI specification into vREST NG to drive your API testing that validates the API responses against JSON Schema and also provides powerful response validation capabilities.	JavaScript	❌	✅	✅