DO NOT USE. It will NOT save your hightlights in academic database sites like ProQuest. It might save your highlight for a day or so, but will randomly fail to load them DO NOT RELY ON THIS.

Not reliable. My highlights and notes disappeared after refreshing the page. I think the issue was related with multiple pages having the same title, although different file names. I'm working with local HTML files.

Terrible experience. Everything just disappears after all my effort of highlighting.

Good, very useful idea, sadly not well developped, for example on pages with expandable content, markings are not restored (the "page can change" function does not help).

Crazy resource consumption.
If you use many tabs, please DO NOT INSTALL, or your Firefox will freeze and it will be really hard to remove the extension.

@Developers: no, my computer is not slow (like you replied to another user). You should learn how to optimize your code instead of blaming users that complain about it.