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Best Free & Open Source Alternatives to Postman

Compare 8 open-source Postman alternatives including HTTPie, Hoppscotch, Insomnia and more

If you're looking for the best open-source alternative to Postman, HTTPie is a strong place to start. If it doesn't quite fit your needs, there are plenty of other great options worth exploring, including Hoppscotch, Insomnia, Bruno and Scalar. We've ranked the top alternatives to help you compare your options and find the right fit.

#1 HTTPie

HTTPie

πŸš€ HTTPie Desktop β€” cross-platform API testing client for humans. Painlessly test REST, GraphQL, and HTTP APIs.

HTTPie Overview

HTTPie is a command-line HTTP client designed to make API testing and HTTP requests simple and intuitive. It's built with Python and offers a user-friendly alternative to tools like curl.

Key Features

Intuitive Syntax - HTTPie uses a natural, readable syntax that mirrors how you think about HTTP requests. Instead of complex flags and options, you can construct requests using simple key-value pairs.

JSON Support - Built-in JSON support makes it incredibly easy to send JSON data. HTTPie automatically detects and formats JSON responses for better readability.

Output Formatting - Responses are automatically formatted and syntax-highlighted, making them much easier to read than raw HTTP output.

Session Support - HTTPie can persist cookies, authentication, and custom headers across multiple requests using sessions.

Basic Usage Examples

The general syntax follows the pattern: http [METHOD] URL [ITEM [ITEM]]

# Simple GET request
http GET httpbin.org/get
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#2 Hoppscotch

Hoppscotch

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

Hoppscotch is a lightweight, web-based API development and testing platform. It supports HTTP requests across all standard methods, WebSocket, GraphQL, MQTT, and Server-Sent Events, and organises requests into collections and folders for easy reuse. Pre-request scripts, post-request tests, and environment variables allow teams to build repeatable, dynamic testing workflows.

Additional features include code snippet generation for more than ten programming languages, cURL import and export, authentication support for Basic, Bearer, OAuth 2.0, and OIDC, and shareable request URLs. Desktop and CLI versions complement the web app, and a self-hosted option is available for organisations that need to keep API definitions on their own infrastructure.

Hoppscotch is designed for individual developers and development teams who want a fast, open, and privacy-friendly alternative to heavier API clients, with real-time collaboration and role-based access controls for shared workspaces.

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#3 Insomnia

Insomnia

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

Insomnia is an API development and collaboration platform for designing, testing, and debugging APIs across multiple protocols including REST, GraphQL, gRPC, and WebSockets. It provides a clean interface for constructing requests, inspecting responses, and organising work into collections. Tests can be automated and run as part of CI pipelines, and API specifications can be mocked directly within the tool.

Projects can be stored locally, in a Git repository, or in the cloud, giving teams flexibility over how they manage and share API work. Role-based access controls and team workspaces support collaborative development, and AI-powered features assist with commit messages and smart suggestions. Insomnia also supports MCP client integration for AI agent workflows.

Insomnia is suited to API developers at all scales β€” from individual contributors using the free tier to enterprise teams at organisations like Netflix, PayPal, and Tesla who need a secure, extensible platform for managing complex API landscapes.

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#4 Bruno

Bruno

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

Bruno is a Git-native API client for testing REST, GraphQL, and gRPC APIs. Unlike cloud-based alternatives, Bruno stores all collections as plain text files in folders on your local machine, making them version-controllable alongside your source code and shareable through standard Git workflows β€” without requiring any account or cloud sync.

The client is designed to be lean and developer-focused, with no bloat or mandatory telemetry. Because collections live in your repository, access control and audit trails are handled naturally through your existing Git permissions and history. Bruno also supports scripting for pre- and post-request logic, environment variables, and secret management.

Bruno is an excellent fit for developers and security-conscious teams who want fast, local-first API testing that integrates natively into their existing version control and code review processes.

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#5 Scalar

Scalar

Scalar is an open-source API platform:γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€πŸŒ Modern Rest API Clientγ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€πŸ“– Beautiful API Referencesγ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€γ€€βœ¨ 1st-Class OpenAPI/Swagger Support

Scalar is an API development platform centred on the OpenAPI standard, providing integrated tooling for documentation, client testing, SDK generation, and API registry management. Its documentation platform renders beautiful, interactive API references from OpenAPI specs and Markdown files, with GitHub synchronisation to keep docs in step with code changes. The API client is a fully open-source, offline-first alternative to Postman for testing and exploring endpoints.

SDK generation automatically produces type-safe client libraries in TypeScript, Python, Go, PHP, Java, and Ruby from an OpenAPI specification. The API registry centralises versioning and management of OpenAPI documents, JSON schemas, and Spectral rulesets with Git integration, providing a single source of truth for API definitions across an organisation.

Scalar is designed for developers and engineering teams who want their API toolchain built on open standards, with consistent documentation, generated SDKs, and a testable client all derived from the same source specification.

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#6 Yaak

Yaak

The most intuitive desktop API client. Organize and execute REST, GraphQL, WebSockets, Server Sent Events, and gRPC 🦬

Yaak is designed to let you send and organize requests for multiple API types:

  • REST, GraphQL, WebSocket, Server-Sent Events (SSE), and gRPC
  • Built using Tauri, Rust, and React
  • Lightweight and privacy-friendly β€” no enforced cloud storage, minimal telemetry, fully offline capable
  • Supports importing collections from other tools like Postman and Insomnia
  • Offers flexible authentication options: OAuth2, JWT, Basic Auth, and encrypted secrets

πŸ”— GitHub Repository


πŸ’‘ Why You Might Like It

  • 🧩 All-in-one API tool β€” handle REST, GraphQL, WebSockets, and gRPC in a single app
  • πŸ”’ Privacy-focused β€” work locally without cloud lock-in
  • πŸ—‚οΈ Organized workflow β€” supports workspaces, folders, and environment variables for dev/stage/prod
  • 🧠 Git-friendly β€” stores data in files that can be versioned alongside your code
  • ⚑ Modern tech stack β€” built with Rust + React + Tauri for speed and security

⚠️ Things to Keep in Mind

  • Some features are still evolving compared to mature tools like Postman or Insomnia
  • Currently has a β€œbug-fix only” contribution policy (no major new features for now)
  • Migrating existing environments may take a bit of setup

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#7 Hurl

Hurl

Run and test HTTP requests with plain text β€” a simple yet powerful command-line tool for API testing.

Hurl is a command-line tool that lets you run and test HTTP requests using simple plain-text files. Built on top of libcurl, it offers a readable, diff-friendly format for defining requests, assertions, and captures β€” making it ideal for automated API testing, continuous integration pipelines, and command-line workflows.

Unlike GUI-based API clients, Hurl stores tests as plain text that can be version-controlled, reviewed in pull requests, and executed anywhere without a graphical environment. It supports HTTP headers, query parameters, form data, multipart uploads, cookies, and can capture values from responses to chain requests together.

Hurl is well-suited for developers and DevOps engineers who prefer CLI-first workflows, want reproducible API tests as code, and need a lightweight alternative to heavy GUI clients or complex testing frameworks.

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#8 Voiden

Voiden

Design, test and document APIs in plain Markdown with a git-native, offline-first approach.

Voiden is a Git-native API client that lets you design, test, and document APIs entirely in plain Markdown. Instead of proprietary collection formats, Voiden uses human-readable API blocks that live alongside your codebase β€” making collections fully version-controllable, reusable, and diffable through standard Git workflows.

The tool supports REST, GraphQL, and WebSocket APIs, and includes features for composing requests, managing environments, and generating OpenAPI documentation. Being offline-first with no mandatory cloud sync or account requirement, Voiden keeps your API workflows local and private by default.

Voiden is well-suited for developers and teams who prefer Markdown-based documentation, want tight integration between API testing and their documentation pipeline, and value the portability and transparency of plain-text formats over locked-in proprietary clients.

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Frequently Asked Questions

Are there any open source alternatives to Postman?

Yes, there are 8 open source alternatives to Postman. Popular options include HTTPie, Hoppscotch, Insomnia and more. These alternatives are free to use and many offer self-hosting options.

What is the best free alternative to Postman?

The best free alternative to Postman depends on your specific needs. HTTPie is a popular choice with self-hosting capabilities. All alternatives listed here are open source and free to use.

Can I self-host an alternative to Postman?

Yes, 1 of the alternatives listed here can be self-hosted, giving you complete control over your data and privacy.

Why should I switch from Postman to an open source alternative?

Open source alternatives to Postman offer several advantages: no vendor lock-in, complete data ownership, no subscription fees, the ability to self-host for privacy and security, and active community support. You can also customize the software to fit your specific needs.

Postman

Postman

Postman is an all-in-one API platform that helps developers design, build, test, document, and monitor APIs. It provides an easy-to-use interface for sending requests, inspecting responses, and automating workflows, making it a go-to tool for working with APIs of any size or complexity.

Beyond simple request testing, Postman supports the full API lifecycle. Teams can collaborate in shared workspaces, create mock servers, automate tests, generate documentation, and integrate with CI/CD pipelines. Its robust set of tools and integrations streamlines API development and ensures consistency, security, and scalability across projects.

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