ARCHIVING RESOURCES:
For FireFox
Save Page WE [to save to local hdd pages that don't archive well like Istagram - the html file is tiny!]
Save a complete web page (as curently displayed) as a single HTML file that can be opened in any browser. Choose which items to save. Define the format of the saved filename. Enter user comments.
https://addons.mozilla.org/en-US/firefox/addon/save-page-we/?src=search
The Archiver
Save Pages to Wayback Machine & Archive.is through a context menu. (in a new tab)
Supports these contexts: pages, images and links.
https://addons.mozilla.org/en-US/firefox/addon/the-archiver/?src=search
For Opera
View Page Archive & Cache
Version 1.7.2 by dessant
View archived and cached versions of web pages on 10+ search engines, such as the Wayback Machine, Archive.is, Google, Bing, Yandex, Gigablast, WebCite, Sogou, Memento, Naver and Yahoo Japan.
https://github.com/dessant/view-page-archive