| Fullscreen On Load | | - | | |
| FullscreenBorder | | - | | |
| Fuzzy Time | | - | | |
| FxUI Editor | | - | | |
| GMarks | | - | | |
| GlobalFindBar | | - | | |
| Go to random tab | | - | | |
| GoTo Tab number | | - | | |
| Googwiki | | - | | |
| Gradientus | | - | | |
| GrepSidebar | | - | | |
| HandySearch | | - | | |
| Hard Refresh | | - | | |
| HashColouredTabs+ | | - | | |
| Height for Side-Bar | | - | | |
| Hidden Menu Web Title | | - | | |
| Hidden UI Elements | | - | | |
| Hide Add-on-Bar-Close-Button | | - | | |
| Hide BookmarksBar | | - | | |
| Hide Caption Titlebar Plus | | - | | |
| Hide Find Bar | | - | | |
| Hide Firefox AppMenu Button | | - | | |
| Hide Menubar | | - | | |
| Hide Navigation Bar | | - | | |
| Hide Plugin Notifications | | - | | |
| Hide Sync in Menu | | - | | |
| Hide Tab Bar With One Tab | | - | | |
| Hide Tabbar | | - | | |
| HideScrollbars | | - | | |
| HideTab | | - | | |
| Highlight Tab | | - | | |
| Highlight Tabs | | - | | |
| History Button | | - | | |
| History Sidebar Button | | - | | |
| History Submenus | | - | | |
| History Submenus Ⅱ | | - | | |
| HoldTab | | - | | |
| Home Double Click Extension | | - | | |
| Homepage New Tab | | - | | |
| Horizontal Scroll | | - | | |
| Hostname in Title bar | | - | | |
| Hostname in Window Title | | - | | |
| Hostname in title | | - | | |
| Hugo Search All Tabs | | - | | |
| I Hate Tabs - SDI for Firefox | | - | | |
| Iconic Firefox Menu | | - | | |
| IdentFavIcon | | - | | |
| Important Tabs | | - | | |
| Improved searchbar | | - | | |
| In tab | | - | | |
