Postman is a widely used tool for working with APIs, but it's not the only one out there. Developers seeking open source alternatives often want more speed, control, or a better fit for their workflow. Fortunately, the ecosystem is rich with options that prioritize different values like performance, collaboration, simplicity, or local-first development.
Hoppscotch
Hoppscotch delivers speed and simplicity without sacrificing power. It starts fast and stays fast, thanks to a lightweight interface and progressive web app architecture. From REST to GraphQL, from WebSockets to Server-Sent Events, it covers a broad range of protocols and formats. What makes it truly stand out is its real-time performance and customizability. You can tweak the UI with themes and Zen mode or use it completely offline. And when it comes to teamwork, Hoppscotch handles shared collections, cloud sync, and access control without adding friction. It’s designed with both the solo dev and collaborative team in mind.
Insomnia
Insomnia leans into completeness. It's not just an API client, it’s an all-in-one API design, testing, and collaboration platform. It supports everything from REST and GraphQL to gRPC and WebSockets, giving you full coverage for modern development. API design is built in, with OpenAPI support, live previews, and in-app test suites. For those integrating with CI/CD pipelines, Insomnia offers a CLI and strong Git support. Whether you're mocking endpoints or syncing secure workflows via E2EE cloud storage, it provides a full lifecycle API experience without leaving your editor.
HTTPie
HTTPie rethinks how HTTP should feel in the terminal. It's elegant, readable, and expressive, crafted to make API testing as human-friendly as possible. With colorized output, natural syntax, and built-in JSON handling, it's a dream for developers who live in the command line. And it doesn't stop there. HTTPie for Web & Desktop brings the same clarity to a graphical interface, proving that simplicity and power aren’t mutually exclusive. It’s not trying to be everything, just the best at keeping you in the flow when working with HTTP.
Bruno
Bruno goes fully offline and fully local. Instead of pushing you into a cloud platform, it stores collections as plain text files using a readable format called Bru. Everything lives in your file system, versioned and tracked via Git. That Git-native, local-first approach defines Bruno’s philosophy, prioritizing privacy, portability, and developer control. It’s fast, cross-platform, and intentionally minimal. If you prefer tools that respect your autonomy and integrate neatly into code-based workflows, Bruno offers a thoughtful, no-nonsense experience that just works.
Each of these tools brings its own vision of what working with APIs should feel like. Whether you value real-time performance, seamless Git integration, full lifecycle support, or a beautifully simple terminal experience, there's an open source option here built to meet you where you are.