Firefox retains data in forms that websites allow Firefox to cache. You'll be surprised by this from time to time as you revisit pages and see, say, an unposted forum response you started composing. Firefox keeps a lot of page data (including session cookies) in your session history file for reasonably good crash recovery. (Of course, this assumes you use regular non-private windows and don't block saving history.) However, sites often want to avoid glitches and preserve privacy by demanding that pages be reloaded fresh on every visit. This is not something Firefox is likely to completely disregard because a top design objective is having websites work the way they are designed to work. And that definitely creates an opening for add-ons. Starting in Firefox 57, extensions will have more limited access to Firefox's internals and many extensions will no longer be useful without those powers. I don't know how Lazarus works, but saving data out of a web page as you work doesn't sound as though it should require superpowers, so hopefully someone can create a new extension with the features users find most critical. As a point of reference, you can search the Chrome extensions store. The reason is that Firefox has added an interface called WebExtensions which is very similar to how Chrome extensions interact with Chrome. Most extensions that run on Chrome could be revised to run on Firefox (by someone experienced with Chrome extensions, not by me!), if not now, starting in Firefox 54. For example: Lazarus: Form Recovery for Chrome https://chrome.google.com/webstore/detail/lazarus-form-recovery/loljledaigphbcpfhfmgopdkppkifgno/ It has very conflicting reviews, so my guess is that doesn't work equally well on all sites.