For custom meta boxes we recommend looking at the following plugins:
Advanced Custom Fields
Advanced Custom Fields is the perfect solution for any WordPress website which needs more flexible data like other content management systems.
If you’re like us and prefer to write your fields in PHP you should checkout out our ACF package. It provides a simple API to create your custom fields in PHP. Visit the documentation to read more about the package.
Papi has a different approach on how to work with fields and page types in WordPress. The idea is coming from how Page Type Builder in EPiServer works and has been loved by the developers.
Papi don’t have a admin ui where you create your fields, it’s done by code and that’s how it should be - Papi