browser-extension-developer

Cross-browser extensions require a shared manifest.json following MV3 standards, with platform-specific API handling. Initialize your project under browser/, configure manifest.json for MV3 compatibility, then test across browsers by loading the unpacked extension in each one. This skill streamlines that setup and validates configurations automatically.

Content scripts inject into web pages to interact with DOM and page context, while background scripts run in the extension's isolated environment and handle persistent logic. Both require separate entrypoints in your manifest.json. This skill manages both script types and their MV3-compliant configurations across browsers.

Manifest V3 migration involves updating manifest.json syntax, converting background pages to service workers, and adjusting content script permissions. This skill enforces MV3-compatible configurations and automates the migration workflow, reducing errors common in manual updates across Chrome, Firefox, and Edge.

Yes. Extensions use i18n localization files stored in public/_locales with language folders. This skill maintains translations across 12 languages and ensures consistent messaging in content and background scripts, then validates all locales during the build process.

Core extension logic can be shared, but Chrome, Firefox, and Edge have API differences requiring conditional handling. This skill consolidates cross-browser API considerations into a repeatable workflow, letting you write once and test across platforms without duplicating entire codebases.