Submit
Ad
 
Learn More

Open Source API Development & Testing Tools

A curated collection of the best open source tools and services for developing Application Programming Interfaces.

See also:API ClientsAPI Infrastructure
Favicon of Hoppscotch

Hoppscotch

Sleek, intuitive API development and testing platform

  • Stars

    80,181

  • Last commit

    3 days ago

  • License

    MIT
Lightweight, fast, and feature-rich API client for developers. Test, debug, and document APIs with ease in a clean, modern interface.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Bruno

Bruno

Lightweight, fast, and open-source API client for developers

  • Stars

    46,718

  • Last commit

    13 hours ago

  • License

    MIT
A modern, user-friendly API client that simplifies API testing and development with a clean interface and powerful features.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Insomnia

Insomnia

Powerful API development and testing made effortless

  • Stars

    39,983

  • Last commit

    12 hours ago

  • License

    Apache-2.0
Intuitive API client for REST, GraphQL, and gRPC. Debug, test, and collaborate on APIs with ease across platforms.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Yaak

Yaak

Fast, secure, offline API client with Git integration

  • Stars

    19,149

  • Last commit

    17 hours ago

  • License

    MIT
A modern API client offering local-only data storage, Git integration, plugin extensibility, and multi-protocol support for developers.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Apache APISIX

Apache APISIX

High-performance API gateway with built-in LLM support

  • Stars

    17,072

  • Last commit

    14 hours ago

  • License

    Apache-2.0
Apache APISIX is an open-source API gateway built on NGINX and etcd, offering dynamic routing, 100+ plugins, load balancing, authentication, and traffic management for APIs and LLM workloads.

Open Source Alternative to:

Favicon of Kong
Kong
Favicon of Scalar

Scalar

Open-source API documentation and testing platform

  • Stars

    16,043

  • Last commit

    15 hours ago

  • License

    MIT
Scalar is an open-source tool for building, customizing, and hosting interactive API documentation with OpenAPI support.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Tyk

Tyk

Universal API management for REST, GraphQL, gRPC & async

  • Stars

    10,812

  • Last commit

    12 hours ago

  • License

    Unknown
Fast, scalable API management platform with open source gateway, analytics, dev portal and dashboard. Deploy anywhere with AI-ready governance and security.

Open Source Alternative to:

Favicon of Kong
Kong
Favicon of Mockoon

Mockoon

Effortless API mocking for seamless development

  • Stars

    8,390

  • Last commit

    12 hours ago

  • License

    MIT
Create, run, and share mock REST APIs without coding. Boost productivity with an intuitive interface and powerful features.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Requestly

Requestly

Intercept, modify, and debug HTTP(S) requests effortlessly

  • Stars

    6,755

  • Last commit

    14 hours ago

  • License

    AGPL-3.0
A powerful browser extension and desktop app for developers to manipulate network requests, debug APIs, and improve web app testing

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of UnKey

UnKey

Secure, scalable API key management for developers

  • Stars

    5,429

  • Last commit

    12 hours ago

  • License

    AGPL-3.0
Streamline API authentication with UnKey's powerful, developer-friendly platform for creating, revoking, and monitoring API keys.

Open Source Alternative to:

Favicon of Kong
Kong
Favicon of HTTPie

HTTPie

Modern command-line HTTP client for the API era

  • Stars

    4,036

  • Last commit

    1 year ago

  • License

    BSD-3-Clause
Intuitive, user-friendly CLI tool for making HTTP requests, debugging APIs, and testing web services with ease and efficiency.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Krakend

Krakend

Blazing-fast API gateway with linear scalability

  • Stars

    2,671

  • Last commit

    1 day ago

  • License

    Apache-2.0
High-performance, stateless API gateway built for microservices. Handle 80K+ requests/second with transparent pricing and enterprise-grade reliability.

Open Source Alternative to:

Favicon of Kong
Kong
Favicon of Firecamp

Firecamp

Unified API development ecosystem for modern teams

  • Stars

    2,609

  • Last commit

    6 months ago

  • License

    AGPL-3.0
All-in-one platform for API testing, documentation, and collaboration, simplifying the entire API development lifecycle.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Voiden

Voiden

Build APIs like code with Git-native workspace

  • Stars

    1,643

  • Last commit

    12 hours ago

  • License

    Apache-2.0
Offline-first API workspace that unifies specs, docs, tests, and mocks in programmable Markdown blocks. Version control everything in plain text files.

Open Source Alternative to:

Favicon of Postman
Postman
Favicon of Tailcall

Tailcall

AI
The modern GraphQL runtime

  • Stars

    1,443

  • Last commit

    8 days ago

  • License

    Apache-2.0
Swiftly design and ship best-practice GraphQL backends atop existing data sources and APIs.

Open Source Alternative to:

Favicon of Apollo GraphQL
Apollo GraphQL
Favicon of WunderGraph

WunderGraph

Unify APIs, databases, and services effortlessly

  • Stars

    1,260

  • Last commit

    12 hours ago

  • License

    Apache-2.0
A powerful backend framework that simplifies API integration, enhances security, and boosts developer productivity for modern web applications.

Open Source Alternative to:

Favicon of Apollo GraphQL
Apollo GraphQL
Favicon of Hive

Hive

Open-source GraphQL federation platform

  • Stars

    484

  • Last commit

    14 hours ago

  • License

    MIT
A fully open-source schema registry, analytics, and gateway for GraphQL federation and APIs

Open Source Alternative to:

Favicon of Apollo GraphQL
Apollo GraphQL
Favicon of Gravitee

Gravitee

Unified API, event, and AI agent management platform

  • Stars

    448

  • Last commit

    12 hours ago

  • License

    Apache-2.0
Full-lifecycle API management platform that unifies synchronous and asynchronous ecosystems. Manage APIs, event streams, and AI agents with enterprise security and 4x faster gateway performance.

Open Source Alternative to:

Favicon of Postman
Postman
Ad
Favicon

 

  
 
Ad
Favicon