Recode

About

Write your own code, and it will run on every page you visit!

This extension provides a full-featured code editor that runs a module-type script on any page that allows inline scripts in their Content Security Policy. If you want to make modifications to certain websites, or add your own flare to every one, just write your code here, and it will run automatically!

The code you write will run on every page, so filter pages by checking the URL. For instance, if you only want something to happen on google, you might write:
if(location.origin == 'https://www.google.com') { /* Your code here */ }