Simple addon where you can add a word and a custom color and it will highlight it on any (it might not work on some dynamic sites) webpage (can be disabled for specific websites) you visit. Doesn't collect any data; it's all local. Upcoming features:

• Support for selectively enabling the addon on a website instead of selectively disabling it
• Support for partial matches (the addon was originally just for highlighting usernames on a specific site so this was not added)