<s>[INST] How do I create an extension/add-on that will work for both Firefox and Chrome? [/INST] Creating an extension that works for both Firefox and Chrome requires the following steps:
1- Choosing a programming language (JavaScript, HTML and CSS)
2- Creating the extension's functionality
3- Creating two manifest files: manifest.json for chrome, manifest.webmanifest for Firefox.
4- Using browser-specific APIs
5- Packaging and distributing the extension on Chrome web store and Firefox Add-ons website.

Note that, using frameworks like WebExtensions API can help you to create a cross-browser extension with a single codebase and make the process easier.</s>\ <s>[INST] Can it be done automatically somehow, so i dont have to deal with compatability issues? [/INST] The best option for an easy cross-browser extension is to use frameworks like the WebExtensions API. Frameworks often have standardized systems that can deploy to multiple browsers. You can find out more about the possible options for cross-browser extensions at this link: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Build_a_cross_browser_extension</s>