An API can be thought of as an instruction manual for communication between multiple software apparatuses. For example, an API may be used for database communication between web applications. By extracting the implementation and relinquishing data into objects, an API simplifies programming.
Open-Source API Development Ecosystem • https://hoppscotch.io • Offline, On-Prem & Cloud • Web, Desktop & CLI • Open-Source Alternative to Postman, Insomnia
Opensource IDE For Exploring and Testing API's (lightweight alternative to Postman/Insomnia)
The open-source, cross-platform API client for GraphQL, REST, WebSockets, SSE and gRPC. With Cloud, Local and Git storage.
🥧 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
Build product integrations with AI.
A free, open-source developer workspace. Snippets, notes, HTTP requests, calculations, and dev tools in one local-first app.
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.
Official Notion JavaScript Client
📚 A collection of useful resources for building RESTful HTTP+JSON APIs.
🚀 HTTPie Desktop — cross-platform API testing client for humans. Painlessly test REST, GraphQL, and HTTP APIs.
The power of curl, the ease of use of httpie.
An API Client package to access the APIs for NBA.com
A simple API client (postman like) in your terminal
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
PHP Curl Class makes it easy to send HTTP requests and integrate with web APIs
OpenAI API + Ruby! 🤖❤️ GPT-5 & Realtime WebRTC compatible!
API Dash is a beautiful AI-powered open-source cross-platform (Desktop & Mobile) API Client built using Flutter which can help you easily create & customize your HTTP & GraphQL API requests, visually inspect responses and generate API integration code. A lightweight alternative to postman/insomnia.
DummyJSON.com provides different types of REST Endpoints filled with JSON data which you can use in developing the frontend with your favorite framework and library without worrying about writing a backend.