Tracy Rotton

taupecatstudios

Custom taxonomies that were developed prior to the release of WordPress 5.0 (the Gutenberg release) may not be compatible with the WordPress block editor.
Custom taxonomies require that the “show_in_rest” property be set to “true” in order to work with the block editor. “show_in_rest” was added with WordPress 4.7 and the integration of the WordPress JSON REST API. Sites using custom taxonomies that were created prior to this likely do not have this property set. Additionally, the default value for “show_in_rest” is “false” (this is poorly documented), ergo older custom taxonomies will not appear in the WordPress block editor interface.
This plugin will take any custom taxonomy where the “show_in_rest” feature is set to “false” and change it to “true”. It will not add any additional REST properties, such as “rest_base” or “rest_controller_class”. If you need those properties set for any reason, you will need to update your custom taxonomy where it is being registered.

Custom Taxonomies for Blocks

WordPress plugin to convert older custom taxonomies so they can be used in the WordPress blocks interface (a.k.a. Gutenberg).

Amaury Balmer

WordPress 3.1 and up allow for reasonably simple custom taxonomy, this plugin makes it even simpler, removing the need for you to write any code.
Add support for taxonomy with or without hierarchical. Choose the selector type for write post.
Allow to add taxonomy to any objects registered on your installation. This plugin can be coupled with the plugin ACF to a new term meta database that allow to create on fly any field need for the taxonomy. For example, for a “Number” taxonomy, you can add fields : number ID, date of parution, screenshot, etc !
This plugin is developped on WordPress 3.5, with the constant WP_DEBUG to TRUE.
This plugin allows you to add taxonomy just by giving them a name and somes options in the backend. It then creates the taxonomy for you, takes care of the URL rewrites, provides a widget you can use to display a “taxonomy cloud” or a list of all the stuff in there, and it allows you to show the taxonomy contents at the end of posts and excerpts as well. 
To boot, it comes with a set of template tags for those who don’t mind adapting their own theme.
For full info go the <a href="https://github.com/herewithme/simple-taxonomy" rel="nofollow ugc">Simple Taxonomy</a> page.

Simple Taxonomy

WordPress 3.1 and up allow for reasonably simple custom taxonomy, this plugin makes it even simpler, removing the need for you to write any code.

Custom Taxonomies for Blocks vs Simple Taxonomy