Extension.js: Cross-Browser Extension Development

extension.js is a zero-configuration command-line interface (CLI) and development toolkit designed for creating, developing, and building cross-browser web extensions. It streamlines the development workflow by providing integrated tools for producing extensions compatible with major browsers including Chrome, Edge, Firefox, and Safari, all without requiring complex or manual build configurations. The package is currently stable at version 3.13.5 (as of April 11, 2026) and demonstrates a rapid release cadence with frequent patches and minor versions, highlighting active maintenance and quick turnaround on bug fixes and features. Its key differentiators include a 'zero-config' philosophy, native TypeScript support, and first-class integration with popular frameworks like React, aiming to significantly reduce setup overhead for developers targeting diverse browser environments. Beyond its CLI, extension.js also offers a programmatic API for `create` and `develop` operations, enabling custom build pipeline integration.