[Your first extension](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Your_first_WebExtension) [Browser extensions](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions) [Google API reference](https://developer.chrome.com/docs/extensions/reference/) [Building a cross-browser extension](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Build_a_cross_browser_extension) [Firefox extension on youtube](https://www.youtube.com/watch?v=pBF4py60jlQ)
