Plasmo

Plasmo is a modern browser extension development framework that brings the developer experience of Next.js to browser extension creation, enabling developers to build, test, and deploy Chrome, Firefox, Edge, and Safari extensions with hot module replacement, TypeScript support, and React integration without wrestling with the complex configuration traditionally required for extension development. The build system handles manifest generation automatically, creating the appropriate manifest.json for each target browser and extension version, eliminating the manual error-prone process of writing and maintaining manifest files by hand. The component architecture enables developers to write extension UI components including popups, options pages, sidebars, new tab overrides, and content scripts using React, with the framework handling the integration between extension contexts and web pages. The messaging API provides a type-safe communication layer between background scripts, content scripts, and extension UI, simplifying the cross-context data flow that is typically a major source of bugs in extension development. The storage API wraps the browser storage with a React hook integration for reactive data persistence. The development server provides hot reloading across all extension contexts simultaneously, dramatically reducing iteration time during development. The deployment pipeline includes automatic building, bundling, and uploading to the Chrome Web Store. The testing framework supports unit and end-to-end testing of extension functionality. Designed for software developers, web development agencies, startups, and companies building browser extensions.