A list with repos of php scripts writting in one file. KISS!
miniProxy - A simple PHP web proxy. http://joshdick.github.io/miniProxy
simple-file-manager - A Simple PHP file manager. https://github.com/jcampbell1/simple-file-manager
single-php-file-upload - A simple one-file PHP script to upload files to a web server. - https://github.com/gioele/single-php-file-upload
Adminer - Database management in a single PHP file https://www.adminer.org/ - https://github.com/vrana/adminer