Some basic webshells i wrote back in the day..

They all have these main features :
login / logout
remote control
file browser
file editor
file uploader / downloader
cmd
sql

It should be quite easy to add your own modules.

Using any of these scripts on servers you dont own or have permission
is ILLEGAL !
Use for Educational and Research Purposes only.

None of these shells is thoroughly tested.
Functionality may vary depending on the server configuration.