This app doesn't use external Library/Framework. Javascript coding structure might seem like little bit React.js, but it's totally vanilla. And the backend structure is similar to Laravel, however that is also raw PHP.
I've used some ES6 syntax in Javascript codes. So a modern web browser is recommended to check with.
The PHP version I worked on is 7.4.0 However I believe it will work in some of the lower versions too as I haven't written anything based on latest PHP features.
No need for any database. The app stores data in a JSON file. Only storage read/write access is enough.
You can put the project in root or any sub directory and access accordingly.
This app has an .htaccess file. So, the app must be served from apache server and the ‘mod_rewrite’ module must be enabled.