The cross-browser extension framework

Choose the right command for the current phase of extension development, from first scaffold to production validation.

Command chooser

Goal	Command	Example
Scaffold a new project	`create`	`npx extension@latest create my-extension --template=new-react`
Develop with watch mode	`dev`	`extension dev --browser=firefox`
Build production artifacts	`build`	`extension build --browser=chrome,firefox --zip`
Build and launch production output	`start`	`extension start --browser=edge`
Launch existing build output only	`preview`	`extension preview --browser=chrome`
Install a managed browser runtime	`install`	`extension install chrome`
Remove a managed browser runtime	`uninstall`	`extension uninstall chrome`

create to scaffold.
dev for iterative coding and reload cycles.
build for production artifacts.
preview or start for production-like validation.
install or uninstall when you need to manage Extension.js browser runtimes explicitly.