React Cosmos vs React Storybook: What are the differences?

React Cosmos: Sandbox for developing and testing UI components in isolation. It is a dev tool for building scalable, high-quality user interfaces. It's designed to make it easy for you to test and iterate on React components. It makes debugging less painful, and it enables you to create and publish component libraries; React Storybook: Develop and design React components without an 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.

React Cosmos and React Storybook can be primarily classified as "MVC" tools.

Some of the features offered by React Cosmos are:

• Develop one component at a time. Isolate the UI you're working on and iterate quickly. Reloading your whole app on every change is slowing you down
• Bookmark component states, from blank states to edge cases. Your component library keeps you organized and provides a solid foundation of test cases
• Can be used in powerful ways. Including snapshot and visual regression testing, as well as custom integrations tailored to your needs

On the other hand, React Storybook provides the following key features:

• Isolated environment for your components (with the use of various iframe tactics)
• Hot module reloading (even for functional stateless components)
• Works with any app (whether it's Redux, Relay or Meteor)

React Storybook is an open source tool with 60.6K GitHub stars and 6.02K GitHub forks. Here's a link to React Storybook's open source repository on GitHub.