The Advanced Custom Fields (ACF) team published an announcement today, assuring users that Gutenberg compatibility is in the works and will be available in version 5.0 of the free version in September 2018. The plugin, created by Elliot Condon, makes it easy for developers to add custom fields to WordPress edit screens, including posts, users, taxonomy terms, and media.
ACF is widely used with more than a million active installations. Developers have been concerned about whether or not their custom fields would continue to work on their clients’ websites after the new editor makes its debut in WordPress 5.0.
Gutenberg treats legacy metaboxes as second class citizens in the interface, stuffed at the bottom of the new edit screen. Metaboxes should, however, continue to work as expected. The ACF announcement lets developers know what to expect for how their metaboxes will appear inside Gutenberg:
By default, our beloved metaboxes are pushed all the way to the bottom of the screen in an awkward attempt to retain compatibility. This placement feels very much like an afterthought from the Gutenberg developers and creates a disjointed editing experience for those of us (1+ million awesome ACF users) who extend the edit screens with extra fields.