OpenAPI Generator Code Generator

OpenAPI Generator is a free and open-source code generation tool that automatically generates API client libraries, server stubs, documentation, and configuration files from an OpenAPI Specification (OAS, formerly known as Swagger Specification). Created in 2018 as a community-driven fork of Swagger Codegen (due to governance disagreements with SmartBear), OpenAPI Generator has become the standard tool for API code generation, maintained by a large community of contributors. Key features: multi-language support: generates code for over 50 programming languages and frameworks including Java, Python, JavaScript, TypeScript, Go, Rust, C#, C++, Ruby, PHP, Swift, Kotlin, Scala, Dart, Perl, Haskell, Lua, and more. Each language supports multiple frameworks (e.g., for Java: Spring, JAX-RS, Vert.x, Micronaut, Quarkus; for Python: Flask, Django, FastAPI, aiohttp). Client libraries: generates complete API client SDKs with type-safe methods for each endpoint, model classes, authentication handling, retry logic, and request/response serialization. Server stubs: generates server skeleton projects with route definitions, controller interfaces, model classes, and input validation, ready for the developer to implement business logic. Documentation: generates HTML, Markdown, Confluence, and other documentation formats from the OpenAPI spec. Configuration files: generates Postman collections, Apache HTTP Client configurations, GitHub Actions workflows. OpenAPI specification support: fully supports OpenAPI 3.0 and 3.1 specifications (which describe REST APIs using JSON Schema, paths, operations, parameters, request bodies, responses, security schemes). Also supports Swagger 2.0 specs for legacy APIs. Customization: uses Mustache templates that can be overridden for custom code generation. Global and per-generator configuration options. Maven and Gradle plugins for Java projects. CLI and Docker image for CI/CD integration. Java. Apache-2.0.