I was looking for a extension like Tamper Monkey, Unfortunately couldn't find it so I was recommended to use Greasemonkey which then I installed later after and tried it. It works literally the same.

Works well, if you're doing simple changes.

Lacks some features, which alternative script managers have, like options for scripts or wider scripting API.

Из-за этого приложения множество сайтов, которые я посещала, не работало корректно