WXT is an open-source framework for building web extensions, the add-ons that change or extend what a web browser does. It is inspired by Nuxt, a framework for web apps, and aims at a good developer experience and support for all major browsers. The copyright holder is Aaron Klinker, and sponsors fund its development.
A developer writes the extension in TypeScript, and WXT builds Manifest V2 or V3 extensions (the two versions of the manifest file that describes an extension to the browser) for Chrome, Firefox, Edge, Safari and any Chromium-based browser from the same code. WXT generates the manifest from the files in the project. In development mode it updates the interface through HMR (hot module replacement, which swaps changed code without a full reload). WXT also zips, uploads, submits and publishes extensions, works with any front-end framework that has a Vite plugin, and includes tools for bundle analysis.
WXT is free and open source under the MIT license.