Best Open Source API Clients using JSX in 2026

Bruno

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

Stars
43,098
Forks
2,323
Last commit
13 hours ago

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

Open Source Alternative to:

Postman

Insomnia

Powerful API development and testing made effortless

Stars
38,332
Forks
2,279
Last commit
3 hours ago

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

Open Source Alternative to:

Postman

Yaak

Fast, secure, offline API client with Git integration

Stars
18,439
Forks
738
Last commit
5 days ago

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

Open Source Alternative to:

Postman

Requestly

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

Stars
6,639
Forks
638
Last commit
6 days ago

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

Open Source Alternative to:

Postman

Firecamp

Unified API development ecosystem for modern teams

Stars
2,588
Forks
166
Last commit
2 months ago

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

Open Source Alternative to:

Postman

Voiden

Build APIs like code with Git-native workspace

Stars
791
Forks
23
Last commit
2 hours ago

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:

Postman

Stars
Forks
Last commit

Stars
Forks
Last commit

Stars
Forks
Last commit

Stars
Forks
Last commit

Stars
Forks
Last commit

Stars
Forks
Last commit

Bruno

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

Stars
43,098
Forks
2,323
Last commit
13 hours ago

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

Open Source Alternative to:

Postman

Insomnia

Powerful API development and testing made effortless

Stars
38,332
Forks
2,279
Last commit
3 hours ago

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

Open Source Alternative to:

Postman

Yaak

Fast, secure, offline API client with Git integration

Stars
18,439
Forks
738
Last commit
5 days ago

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

Open Source Alternative to:

Postman

Requestly

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

Stars
6,639
Forks
638
Last commit
6 days ago

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

Open Source Alternative to:

Postman

Firecamp

Unified API development ecosystem for modern teams

Stars
2,588
Forks
166
Last commit
2 months ago

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

Open Source Alternative to:

Postman

Voiden

Build APIs like code with Git-native workspace

Stars
791
Forks
23
Last commit
2 hours ago

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:

Postman

Open Source API Clients using JSX

A curated collection of the best open source client applications for interacting with and testing APIs. using JSX.