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Generating OpenAPI Specification (OAS) for your REST APIs

By Abdullah Akbar on April 5,2022

The OpenAPI Specification (OAS) defines a standard, language-agnostic interface to RESTful APIs which allows both humans and computers to discover and understand the capabilities of the service without access to source code, documentation, or through network traffic inspection.[1]

APISec supports 1.0, 2.0, 3.x versions of the OpenAPI specification (OAS) as well as Postman and RAML formats.

The following is a list of some libraries and resources which can be helpful in generating an OpenAPI Specification (OAS) document for your existing REST API application grouped by implementation technology.




  • For JAX-RS based projects(Jersey/RESTEasy/Mule),Swagger Core provides examples and server integrations for generating the Swagger API Specification, which enables easy access to your REST API - GitHub - swagger-api/swagger-core
  • The Swagger Maven Plugin is a JAX-RS & SpringMVC supported maven build plugin, helps you generate Swagger JSON and API document in build phase - GitHub - kongchen/swagger-maven-plugin


  • Flask-RESTX is an extension for Flask which provides a coherent collection of decorators and tools to describe your API and expose its documentation properly using Swagger - GitHub - python-restx/flask-restx
  • Falcon-apispec is an apispec plugin that generates OpenAPI specification (aka Swagger) for Falcon web applications - Github - alysivji/falcon-apispec
  • drf-yasg - Yet another Swagger generator helps in automated generation of real Swagger/OpenAPI 2.0 schemas from Django REST Framework code. - GitHub - axnsan12/drf-yasg
  • drf-spectacular is a sane and flexible OpenAPI 3 schema generation for Django REST framework - GitHub - tfranzel/drf-spectacular


  • swagger-autogen performs the automatic construction of the Swagger documentation - swagger-autogen - npm
  • NestJS provides a dedicated module which allows generating OpenAPI (Swagger) - Github - nestjs/swagger
  • swagger-express is a simple and clean solution to integrate swagger with Express - swagger-express - npm
  • express-oas-generator automatically generates OpenAPI (Swagger) specification for existing ExpressJS 4.x REST API applications - express-oas-generator - npm
  • Hapi-swagger is a OpenAPI (aka Swagger) plug-in for Hapi When installed it will self document the API interface in a project - hapi-swagger - npm


  • swagger-php is a php swagger annotation and parsing library which generates interactive OpenAPI documentation for your RESTful API using doctrine annotations. - GitHub - zircote/swagger-php



  • swag automatically generates RESTful API documentation with Swagger 2.0 - GitHub - swaggo/swag
  • go-swagger (golang implementation of Swagger 2.0) is a complete suite of fully-featured, high-performance, API components to work with a Swagger API: server, client and data model - Github - Swagger 2.0 implementation for go

APISec seamlessly integrates with most of the popular API gateways and automatically pulls the API specs in OAS format for easy API registration. For the purpose of document completion and developer curiosity, a select few are mentioned below.

AWS API Gateway

Google Cloud Endpoints

Azure API Management

Apigee Edge



  1. OpenAPI Initiative