Open source API development ecosystem - https://hoppscotch.io (open-source alternative to Postman, Insomnia)

The open-source, cross-platform API client for GraphQL, REST, WebSockets, SSE and gRPC. With Cloud, Local and Git storage.

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

🥧 HTTPie CLI — modern, user-friendly command-line HTTP client for the API era. JSON support, colors, sessions, downloads, plugins & more.

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

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

A RWKV management and startup tool, full automation, only 8MB. And provides an interface compatible with the OpenAI API. RWKV is a large language model that is fully open source and available for commercial use.

A single API for all your integrations.

Official Notion JavaScript Client

📚 A collection of useful resources for building RESTful HTTP+JSON APIs.

Free and open-source API Client & Interceptor

🚀 HTTPie Desktop — cross-platform API testing client for humans. Painlessly test REST, GraphQL, and HTTP APIs.

Insomnium is a fast local API testing tool that is privacy-focused and 100% local. For testing GraphQL, REST, WebSockets and gRPC. This is a fork of Kong/insomnia

The power of curl, the ease of use of httpie.

PHP Curl Class makes it easy to send HTTP requests and integrate with web APIs

OpenAI API + Ruby! 🤖❤️ GPT-5 & Realtime WebRTC compatible!

An API Client package to access the APIs for NBA.com

A simple API client (postman like) in your terminal

Developer-first OpenSource API DevTool, Postman/Insomnia alternative.

Offline-First Minimalistic HTTP & Socket Testing Client for the Web & Desktop