| PlacesCleaner | | - | | |
| Places Maintenance | | - | | |
| Places Auto Vacuum On Idle | | - | | |
| Pinned Window extension for Firefox | | - | | |
| Personas Shuffler | | - | | |
| Persona Switcher | | - | | |
| Password dialog begone | | - | | |
| Panic Button | | - | | |
| PB Exit | | - | | |
| Options Dialog Restorer (ODR) | | - | | |
| OpenInWindow | | - | | |
| Open sync tabs button | | - | | |
| Open in Private Window | | - | | |
| Open Profile Folder | | - | | |
| Only Minor Update | | - | | |
| Online Reload | | - | | |
| Old Addon Manager | | - | | |
| NoWay | | - | | |
| NoContentDownloadLastDir | | - | | |
| No XPI Install Delay | | - | | |
| No More Install Delay | | - | | |
| No Color | | - | | |
| Nightly Tester Tools | | - | | |
| NewTabURL | | - | | |
| New Tab King | | - | | |
| New Tab JumpStart | | - | | |
| New Private Window | | - | | |
| New Plugin Disabler | | - | | |
| Multiple Addon Deactivator | | - | | |
| Multi-Search | | - | | |
| Mozilla Labs： Prospector - Search Tabs | | - | | |
| Mozilla Labs： Prospector - Home Dash | | - | | |
| Mozilla Archive Format | | - | | 仮対応 |
| More In Content UI + | | - | | |
| Mnenhy | | - | | |
| MinimizeToTray revived (MinTrayR) | | - | | |
| MinimizeToTray Plus | | - | | |
| Minimize On Start and Close | | - | | |
| Mid-Click Restart | | - | | |
| Memory Restart | | - | | |
| Massive Extender | | - | | |
| Locale Switcher | | - | | |
| Load from Cache | | - | | |
| Live HTTP Headers | | - | | |
| LiteRider7 | | - | | |
| Links and Forms | | - | | |
| Link And Forminfo | | - | | |
| LimitedSurf | | - | | |
| Lightweight Themes Manager | | - | | |
| Language Switch | | - | | |