Custom CSS-JS-PHP is a very innovative idea to keep seperate your custom code from plugins & themes so you can upgrade your plugins & themes without losing any change. You can define CSS,JS or PHP code and can apply using shortcode,actions or filters.
Now it's super easy to execute your PHP code anywhere on your wordpress site e.g within pages/posts or custom post types. You need not write a plugin to integrate additional functionality using actions or filters.
This plugin for WordPress, the publicly available If you experience any problems with the plugin, feel free to contact me.