Openapi GitHub Repositories (2026) · Open Source Tools

FastAPI framework, high performance, easy to learn, fast to code, ready for production

Architecture diagrams and checkable docs from your codebase — ERD, C4, API and lifecycle — generated from Prisma, OpenAPI or GraphQL. One HTML file, no server.

Full-stack web application template with FastAPI, React, SQLModel, PostgreSQL, Vite, Tailwind CSS, shadcn/ui, FastAPI Cloud, and Docker Compose.

Opensource IDE For Exploring and Testing API's (lightweight alternative to Postman/Insomnia)

Grab your own cool 'runs-on.dev' subdomain to use for free forever.

Catch API bugs before your users do

Lightweight embeddable web server written in pure C# with few dependencies to 3rd-party libraries.

Super-fast/easy runtime validators and serializers via transformation

Simple, Fast, Code first and Compile time generated OpenAPI documentation for Rust

OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec (v2, v3)

OpenAPI Diff and Breaking Changes

Scalar is an open-source API platform:　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　🌐 Modern REST API Client　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　📖 Beautiful API References　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　✨ 1st-Class OpenAPI/Swagger Support

Generate Swift client and server code from an OpenAPI document.

Generate Pydantic v2 models, dataclasses, TypedDict, and msgspec.Struct from OpenAPI, JSON Schema, GraphQL, Avro, Protobuf, and raw JSON/YAML/CSV.

Swagger UI is a collection of HTML, JavaScript, and CSS assets that dynamically generate beautiful documentation from a Swagger-compliant API.

Powerful, joyful building blocks for modern cloud-native applications.

API Gateway bridging modern and legacy APIs with WSDL-to-OpenAPI, SOAP-to-REST, XML, OAuth2, and GraphQL.

OpenAPI 3.0 and 3.1 and 3.2 (and Swagger v2) implementation for Go (parsing, converting, validation, and more)

Instant REST and MCP APIs for PostgreSQL and MySQL, on existing or new databases. CRUD, custom SQL routes, auth and ACL without writing a backend. Low-code, ⚡ realtime, high-performance. Native MySQL support since v2.5

Self-Hosted API Management for Builders