npm · crates.io100Exceptionalhealth index

scalar/scalarScalar is an open-source API platform: 🌐 Modern REST API Client 📖 Beautiful API References ✨ 1st-Class OpenAPI/Swagger Support
TypeScript · Vue★ 16.1K↓ 8.3M/moSep 16, 2026
npm · Packagist99Exceptionalhealth index

swagger-api/swagger-uiSwagger UI is a collection of HTML, JavaScript, and CSS assets that dynamically generate beautiful documentation from a Swagger-compliant API.
JavaScript★ 29K↓ 49.8M/moSep 16, 2026
npm98Exceptionalhealth index
Java · TypeScript · C#★ 5,837↓ 2.1M/moAug 28, 2026
npm98Exceptionalhealth index
JavaScript · TypeScript★ 9,461↓ 49.5K/moAug 28, 2026
Maven96Exceptionalhealth index

OpenAPITools/openapi-generatorOpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec (v2, v3)
Java★ 26.7KSep 16, 2026
PyPI96Exceptionalhealth index

fastapi/fastapiFastAPI framework, high performance, easy to learn, fast to code, ready for production
Python★ 102.4K↓ 414M/moSep 16, 2026
PyPI · NuGet · npm96Exceptionalhealth index
C#★ 3,822Sep 12, 2026
npm96Exceptionalhealth index

stoplightio/prismTurn any OpenAPI2/3 and Postman Collection file into an API server with mocking, transformations and validations.
TypeScript★ 5,017↓ 3.3M/moAug 27, 2026
npm96Exceptionalhealth index

stoplightio/spectralA flexible JSON/YAML linter for creating automated style guides, with baked in support for OpenAPI (v3.1, v3.0, and v2.0), Arazzo v1.0, as well as AsyncAPI v2.x.
TypeScript★ 3,205↓ 79.5M/moSep 16, 2026
npm96Exceptionalhealth index
JavaScript★ 2,694Aug 27, 2026
npm95Exceptionalhealth index

usebruno/brunoOpensource IDE For Exploring and Testing API's (lightweight alternative to Postman/Insomnia)
JavaScript · TypeScript★ 47K↓ 1.1M/moSep 16, 2026
npm94Exceptionalhealth index

asyncapi/modelinaA library for generating typed models based on inputs such as AsyncAPI, OpenAPI, and JSON Schema documents with high customization
TypeScript★ 448↓ 667.3K/moSep 25, 2026
—94Exceptionalhealth index
C#★ 239Sep 11, 2026
npm94Exceptionalhealth index

mockoon/mockoonMockoon is the easiest and quickest way to run mock APIs locally. No remote deployment, no account required, open source.
TypeScript · HTML★ 8,389↓ 847.8K/moSep 7, 2026
Go94Exceptionalhealth index
Go · Go Template★ 8,542Aug 28, 2026
npm94Exceptionalhealth index
TypeScript★ 100↓ 24.5M/moOct 12, 2026
npm94Exceptionalhealth index

zuplo/zudokuFramework for building high quality, interactive API documentation.
TypeScript★ 591↓ 130.7K/moSep 12, 2026
PyPI92Excellenthealth index
Python★ 1,136Sep 15, 2026
Maven92Excellenthealth index

swagger-api/swagger-codegenswagger-codegen contains a template-driven engine to generate documentation, API clients and server stubs in different languages by parsing your OpenAPI / Swagger definition.
Mustache · Java★ 17.8KOct 18, 2026
Maven92Excellenthealth index
Java★ 868Oct 8, 2026
NuGet91Excellenthealth index
C#★ 416Sep 11, 2026
Go91Excellenthealth index
Go★ 1,358Sep 14, 2026
Maven91Excellenthealth index

specmatic/specmaticEliminate API integration headaches with Specmatic's no-code AI-powered API development suite. Teams ship APIs 10x faster by transforming specifications into executable contracts instantly—no coding required, no integration surprises.
Kotlin★ 396Sep 9, 2026
npm91Excellenthealth index

stoplightio/elementsBuild beautiful, interactive API Docs with embeddable React or Web Components, powered by OpenAPI and Markdown.
TypeScript★ 2,457↓ 719.6K/moSep 9, 2026
Go · npm90Excellenthealth index

go-fuego/fuegoGolang Fuego - Web framework generating OpenAPI 3 spec from source code - Pluggable to existing Gin & Echo APIs
Go★ 1,776Oct 19, 2026
PyPI90Excellenthealth index
Python★ 1,988Sep 14, 2026
PyPI89Excellenthealth index

marshmallow-code/apispecA pluggable API specification generator. Currently supports the OpenAPI Specification (f.k.a. the Swagger specification)..
Python★ 1,219Sep 14, 2026
npm88Excellenthealth index
TypeScript★ 1,974Sep 14, 2026
npm88Excellenthealth index

cloudflare/chanfanaOpenAPI 3 and 3.1 schema generator and validator for Hono, itty-router and more!
TypeScript★ 766↓ 302.1K/moSep 18, 2026
npm · PyPI88Excellenthealth index

counterfact/api-simulatorTurn an OpenAPI spec into a local API in one command. Build and test your frontend with custom responses, shared state, and simulated failures, without waiting for the backend.
TypeScript · JavaScript · Astro★ 170↓ 28.2K/moSep 18, 2026