Expo Sketch vs ReactXP: What are the differences?
Expo Sketch: A Playground for React Native. Instantly test your code on a device, or in the browser. You can either preview the component on the emulator inside the browser, or open it directly on your device with the Expo app. The UI updates as you type — every keystroke, without having to hit save; ReactXP: A library for cross-platform app development using React and React Native, by Microsoft. With React and React Native, your web app can share most of its logic with your iOS and Android apps, but the view layer needs to be implemented separately for each platform. We have taken this a step further and developed a thin cross-platform layer we call ReactXP. If you write your app to this abstraction, you can share your view definitions, styles and animations across multiple target platforms. Of course, you can still provide platform-specific UI variants, but this can be done selectively where desired.
Expo Sketch and ReactXP belong to "Cross-Platform Mobile Tools" category of the tech stack.
ReactXP is an open source tool with 7.77K GitHub stars and 548 GitHub forks. Here's a link to ReactXP's open source repository on GitHub.