Are you talking about the field API update with WordPress 6.9
Edit 11/25/25: The Miscellaneous Editor Changes developer note was published after the Field Guide. It has been added below. Edit 12/15/25 The Adjacent Post Navigation Changes developer note was pu…
make.wordpress.org
If so, ACF (what you want) and the field API have completely varied use cases.
If the license of ACF Pro is your concern, you can use SCF which is a fork of ACF Pro by WordPress itself.
In 2024, there was a lot of drama between WP Engine (the hosting company and also the company that owns ACF) and Matt from WordPress
This story has been updated throughout with more details as the story has developed. We will continue to do so as the case and dispute are ongoing. The
techcrunch.com
Matt then forked the ACF plugin and called it SCF
Secure Custom Fields boosts content management with custom fields and options. It deactivates Advanced Custom Fields to prevent duplicate code errors.
wordpress.org
It's got almost all features of ACF Pro and is free.