Database tables aliases - a table can have any name, you have just to define alias for each table which is later used in code. This allows to use tables with data for other cmses.
Administration as a separate module. Whole system is working without administration folder on server, while administration folder can be placed on totally different URL or even at your local host.
Reusable classes and methods - many universal functions which can be used for further modules development like
Sending emails
Uploading files
Resizing images
Cropping images
Retrieving paginated data
Creating hierarchical (parent -> children) array from non-hierarchical
Calculating local or UTC time based on users local time
Stripping text to certain amount of characters, generating random strings
Comparing, searching, converting arrays and objects
Connection to databae via PDO extension and using prepared statements for querying database
...
Library of almost 120 jQuery & Bootstrap plugins, CSS frameworks, PHP libraries with capability to attach them to particular page with few cicks or attach them to whole website. Capability to check if new version is available on github. (Planned test pages for all plugins, so if new version is released you can test its compatibility with previous version)
Templating system with use of Smarty template engine. A powerful system, look of your website is handled with one basic file and rest are just small blocks or chunks which can be styled or customized as you wish.
Editing your code directly from administration with live preview of edited page
Modular based system to allow implementation of own functionality according to requirements. If you already have data which you want to display, creating a module is just a matter of few lines of code.
Incredibly fast and light. Performance is priority. There are no useless querries, loops. Every page is using only what it does need. I made sure to eliminate all errors, warnings and notices which may additionally lower performance.
Every visit, on every website is loged into database. You may not need it, but it will give you great overview about your visitors.
Plays good with PHP 7.3, Maria DB 10.3, Memcached and Pagespeed