https://chrome.google.com/webstore/detail/wayback-machine/fpnmgdkabkmnadcjpehmlllkndpkmiak
https://addons.mozilla.org/en-CA/firefox/addon/wayback-machine_new/
It will also detect when a webpage you are trying to visit is dead and will offer to replay an archived version
Purely to contribute to the internet archive. There’s the “save page now” button that’ll save the webpage to your account, but the automatic downloader that I refer to in the post doesn’t do that and is purely for the sake of expanding the archive.