Auto-Sort Bookmarks
Auto-Sort Bookmarks is a free to use browser tool that comes in the form of a browser add-on for Mozilla Firefox. The add-on provides you with the convenience of having a bookmarks list that is automatically sorted in an alphabetical order.
From the preferences of the add-on, you can select the add-on to automatically maintain the alphabetical order of your bookmarks. If you disable this option, you can do a manual sort with a button on your toolbar. You can also opt to place folders before regular bookmarks and also apply your options to the bookmarks toolbar.