| My Reading Mode | | - | | |
| Multi Word Finder | | - | | |
| MouseoverDictionary | | - | | |
| MouseZoomer | | - | | |
| MouseZoom | | - | | |
| Monochromer | | - | | |
| Monochro | | - | | |
| Minimum Font Size Per Domain | | - | | |
| Minimum Font Size Hotkey | | - | | |
| Minimal Site Block | | - | | |
| Metric Cooking | | - | | |
| Magnifier-Zoom | | - | | |
| Long URL Please | | - | | |
| LinkRedirector | | - | | |
| Link Toggler | | - | | |
| Link Stalker | | - | | |
| Light Switch | | - | | |
| LetGo | | - | | |
| Leet Key | | - | | |
| Kill It | | - | | |
| Kill Button | | - | | |
| Karma Blocker | | - | | |
| Javascript Firewall | | - | | |
| JSONovich | | - | | |
| JS Injector | | - | | |
| Invert Colors | | - | | |
| ImgLikeOpera | | - | | |
| ImageFit | | - | | |
| Image Zoom | | - | | |
| Image Mikirenaizer | | - | | |
| IPA furigana | | - | | |
| IE View Lite | | - | | |
| IE View | | - | | |
| IE Tab Plus | | - | | |
| IE Tab 2 (FF 3.6+) | | - | | |
| IE Tab + | | - | | |
| IE Tab | | - | | |
| I Dislike Amazon Affiliate! | | - | | |
| Humans.txt | | - | | |
| Hover Nofollow | | - | | |
| Highlightor | | - | | |
| HighlightAll | | - | | |
| Highlight NoFollow links | | - | | |
| HideIt | | - | | |
| Hide to Print | | - | | |
| Hide all Images | | - | | |
| Hide Mouse Pointer | | - | | |
| Hidden Furigana | | - | | |
| HeadingsMap | | - | | |
| Harmful Web Contents Cleaner | | - | | |