Two simple tools that are helpful in everyday activity are shown below.
Caution: File upload is always a major security issue !
Note: The following applies for a standard Apache-PHP-HTML-CSS-JS website, but much of it is valid in other cases too.
File download consists of front-end GUI and back-end code .
Caution: Never use include or require for uploaded files. Serve them as static or use file_get_contents(), readfile() etc.
Basic HTML5 template that you may start any project with.