Open source openapi projects
Every project in the registry tagged openapi, ranked by real GitHub adoption.
One interface for every AI model you run or connect
FastAPI framework, high performance, easy to learn, fast to code, ready for production
Lightweight, fast, and open-source API client for developers
The OpenAPI Specification Repository
OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec
📘 OpenAPI/Swagger-generated API Reference Documentation
🚀 Self-hosted TikTok & Douyin scraper and no-watermark video downloader — async REST API, MCP server, CLI and web console for posts, profiles, comments and pla
gRPC to JSON proxy generator following the gRPC HTTP spec
Open-source API documentation and testing platform
Automatically generate RESTful API documentation with Swagger 2.0 for Go.
Expose your FastAPI endpoints as Model Context Protocol (MCP) tools, with Auth!
💨 Fast, Async-ready, Openapi, type hints based framework for building APIs
Light, flexible and extensible ASGI framework | Built to scale
Effortless API mocking for seamless development
Generate TypeScript types from OpenAPI 3 specs
Examples and server integrations for generating the Swagger API Specification, which enables easy access to your REST API
The Swagger/OpenAPI toolchain for .NET, ASP.NET Core and TypeScript.
Design-first Go framework that generates API code, documentation, and clients. Define once in an elegant DSL, deploy as HTTP and gRPC services with zero drift b
Super-fast/easy runtime validators and serializers via transformation
Typesafe APIs Made Simple 🪄
👨🚀 Turn API specifications into production-ready SDKs, validators, mocks, and more. 20+ plugins. Millions of weekly npm downloads. Used by Vercel, OpenCode,
package for building REST-style Web Services using Go
OpenAPI (f.k.a Swagger) Specification code generator. Supports C#, PowerShell, Go, Java, Node.js, TypeScript, Python
The first AI agent that builds permissionless integrations through reverse engineering platforms' internal APIs.
Input OpenAPI. Output SDKs and Docs.
Catch API bugs before your users do
Simulate API failures, throttling, and chaos — all from your command line.
Port OpenAPI Specs to Postman Collections, inject test suite and run via Newman 👨🏽🚀
Transform documentation with developer-focused simplicity
Related tags
Frequently asked questions
How many open source openapi projects are there?
This registry tracks 29 projects tagged openapi, with 563,111 GitHub stars between them. The most-adopted is Open WebUI at 152,394 stars.
Are these openapi projects free to use?
Yes — 28 of the 29 carry an explicit open-source licence across 4 distinct licences, so there is no licence fee. Where a project also sells a hosted or enterprise version, the self-hosted path remains free.
Which openapi project should I choose?
The list above is ranked by GitHub stars, but stars measure attention rather than fit. Check three things on each card: the licence (permissive versus copyleft), the language it is written in, and the last-push date — a high-star project that has not been pushed in a year is a liability.
Are these openapi projects still maintained?
28 of the 29 were pushed in the last 90 days, and every card shows its exact last-push date so you can see the rest. Sort your shortlist by that date before committing to a migration.