The description of [Wayback/Archive] GitHub – dessant/web-archives: Browser extension for viewing archived and cached versions of web pages, available for Chrome, Edge and Safari is missing Firefox and Opera, but in the meantime the extension is available in these stores for:
As a great example of how to write a browser plugin for all these architectures, it shows how to write this in mostly JavaScript with Vue.js with a tiny bit of play HTML.
Web Archives is a plugin that lets you search either the URL from the current browser tab, or a URL you type, within various archival sites (all Wikipedia links):





