Tamagui is a bunch of libraries for building UIs that share code across React and React Native.

The open-source notifications infrastructure. A fully-featured microservice to send SMS, E-mail, Slack and Push notifications. Embeddable notification center for React with real-time updates, content management, and much more...

Expo is a framework and a platform for universal React applications. It is a set of tools and services built around React Native and native platforms that help you develop, build, deploy, and quickly iterate on iOS, Android, and web apps from the same JavaScript/TypeScript codebase.

Inertia.js lets you quickly build modern single-page React, Vue and Svelte apps using classic server-side routing and controllers.

Tina is an open-source site editing toolkit for React-based sites like Next.js & Gatsby to build content management directly into your website.

A React-powered node editor and runtime engine. Build apps that are resilient to changing requirements by modeling your business logic as a JSON graph. Flume provides a sleek UI for creating and editing these graphs.

Ink provides the same component-based UI building experience that React offers in the browser, but for command-line apps. It uses Yoga to build Flexbox layouts in the terminal, so most CSS-like props are available in Ink as well. If you are already familiar with React, you already know Ink.

Gatsby is a modern framework for blazing fast websites, made with React and GraphQL.

Sanity is a headless, real-time CMS where the front end is an open source React-based construction kit and the back end is a graph-oriented cloud datastore with a globally distributed CDN.

Jest is used by Facebook to test all JavaScript code including React applications. Complete and easy to set-up JavaScript testing solution. Works out of the box for any React project. Fast interactive watch mode runs only test files related to changed files and is optimized to give signal quickly. Capture snapshots of React trees or other serializable values to simplify testing and to analyze how state changes over time.

Styletron is a universal CSS-in-JS engine built from the ground up for high-performance.

A toolkit for React, Preact & Inferno apps, React libraries and other npm modules for the web, with no configuration (until you need it)

A JavaScript framework for building data-driven React applications.
Never again communicate with your data store using an imperative API. Simply declare your data requirements using GraphQL and let Relay figure out how and when to fetch your data.
Queries live next to the views that rely on them, so you can easily reason about your app. Relay aggregates queries into efficient network requests to fetch only what you need.
Relay lets you mutate data on the client and server using GraphQL mutations, and offers automatic data consistency, optimistic updates, and error handling.

React Native lets you build mobile apps using only JavaScript. It uses the same design as React, letting you compose a rich mobile UI from declarative components.

Enzyme is a JavaScript Testing utility for React that makes it easier to assert, manipulate, and traverse your React Components' output.

A minimalistic framework for server-rendered React applications

Redux is a predictable state container for JavaScript apps.

It helps you write applications that behave consistently, run in different environments (client, server, and native), and are easy to test. On top of that, it provides a great developer experience, such as live code editing combined with a time traveling debugger.

You can use Redux together with React, or with any other view library.

Isolate your React UI Component development from the main app. Now you can develop and design React UI components without running your app. You just load your UI components into the React Storybook and start developing them.
This functionality allows you to develop UI components rapidly without worrying about the app. It will improve your team’s collaboration and feedback loop.

An easier, faster way to build apps with React and JavaScript. Built from the ground up to target multiple platforms. Customize every piece of it from colors to styles. Interactive animations brings your apps to life.

N1 is an open-source mail client built on the modern web with Electron, React, and Flux. It is designed to be extensible, so it's easy to create new experiences and workflows around email. N1 is built on the Nylas Sync Engine which is also open source free software.