GitHub - makeitworkpress/wp-custom-fields: WP Custom Fields is an options, metabox and customizer framework for WordPress aimed at speeding-up plug-in and theme development.
Meta Box - WordPress Custom Fields and Custom Meta Boxes Framework
4 Best Meta box Plugins for WordPress 2022 Trusted by Developers
How to Add Related Posts to WordPress Using Meta Box | by Janessa Tran | Meta Box | Medium