The best open source alternative to Postman is Insomnia REST Client. If that doesn't suit you, our users have ranked more than 100 alternatives to Postman and loads of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Postman are Hoppscotch, HTTPie for Terminal, Bruno and soapUI.
A powerful REST API Client with cookie management, environment variables, code generation, and authentication for Mac, Window, and Linux.
Hoppscotch is an open-source API development ecosystem. It helps you create your requests faster, saving you precious time on your development.
HTTPie (pronounced aitch-tee-tee-pie) is a command line HTTP client. Its goal is to make CLI interaction with web services as human-friendly as possible. It provides a simple http command that allows for sending arbitrary HTTP requests using a simple and natural syntax, and...
Lightweight open source API client offering offline API testing, local filesystem storage via plain text, version control compatibility with git, intuitive request management, privacy-first design, cross-platform support, minimal resource usage, and community-driven development.
Eviware, the maker of soapUI, Web Service Testing Leader
soapUI is a tool for functional testing, mainly of web services like SOAP based web services and RESTful web services, but also HTTP based services and JMS Services as well as databases. soapUI is an open source and compl.
API testing tool. Which allows web developers to create and test custom HTTP requests.
The API client for modern developers. Call REST, GraphQL, and gRPC APIs from a simple and intuitive app.
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.
ApiArk is a local-first API client built with Tauri v2 and Rust. No login, no cloud, no telemetry. Supports REST, GraphQL, gRPC, WebSocket, SSE and MQTT from one interface. Collections are stored as plain YAML files on your filesystem, fully git-diffable.
HTTP client for GNOME featuring GTK 4 UI, organized project management, request history, secure environment variables, JavaScript scripts for preprocessing, export in cURL and more formats, syntax-highlighted response viewing, and advanced request customization.
Requestly is a lightweight proxy available as a browser extension & desktop app to intercept & modify network requests. Using Requestly you can Modify Headers, Redirect Url, Mock API response, Delay/Throttle requests, etc.
Stoplight is an API Design, Development, and Documentation platform that enables consistency, reusability, and quality, all with an easy, enjoyable developer experience.
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Very similar to Postman, but doesn't require logging in for basic features. So useful for some quick testing.