I have made a JS code and so far it works like a sharp knife, so many thanks for you. I'd suggest for improvements :
1- enable paste option in the code area, you have included copy and cut but I can't past in it.
2- make the same function for android app, I searched a lot but can't find the same thing
3- make the file section more effective, instead of making the user write the pathway of the file, you add an option to select and upload

Can't inject on page load on some sites. Have to click "inject" manually and then everything works.

Easier to use than TamperMonkey or GreaseMonkey

For a long time I was looking for a simple add-on that provides injection of code, not only js (css,html)
I love it
Already use it in many sites for adding elements in page improving site experience.

Thank you for this important add-on!

and Documentation in GitHub saved my time to understand it ^^