Firefox Extension/addon made

Hello. Correct me if I am wrong. You have a list of words stored inside your extension. You can create/update/delete those words. When you hit a button, the extension needs to select every word on the website you are currently on, and change its background to some color. The extension needs to be convivially placed, so you can easily access it. Feel free to hit me up so we can talk more about this project. It shouldn't be hard task, and the budget is ok.

Hello! The idea is clear. User will be able to use keyboard shortcuts, also I suppose need add ability to choose color. Besides this, I suppose will be needed add "navigation panel" like in original "find". WebExtensions API provide the find interface, but it is useless for your task. Although the extension is pretty simple, the amount of work is not too small. Thank you for attention! I forgot mention, that you can use the same extension and with Google Chrome browser.