While reading a wall of text you might want to jump around the page and if there are no links, finding the parts you want to check often can be tedious. This add-on helps you in that goal by allowing you to bookmark those locations.
In the new version (0.5) you can have permanent marks for pages. They will last until you clear them. This is now a default setting for new installs. Or you can change to have volatile marks that disappear if you refresh the page.
You can configure your own key shortcuts (any won't work, for example shortcuts that Firefox uses) for marking and scrolling in the settings.
Permanent marks use IndexedDB for saved images. So they might be deleted in some case. You might need to refresh page to update marks in some edge cases, as if you have the same page (exact URL) open in several tabs or if you switch between permanent and volatile marks.
For usage, see
a demo.
