[diggan]

> Last I saw the browser extensions worked automatically for all pages, thus sending all your browsing habits to some random place

You're right that when a extension want to work when the current tab and site you have in focus, they'll need to ask for permission to all websites (otherwise the developer would have to whitelist all the websites where the extension should work) but that doesn't mean that they are sending your browser habits anywhere. Although they could, so review the source code if possible.