Andr&eacute; Boekhorst

This plugin combines the two of the best WordPress plugins: <a href="https://wordpress.org/plugins/advanced-custom-fields/" title="Advanced Custom Fields" rel="ugc">Advanced Custom Fields</a> and <a href="https://wordpress.org/plugins/json-rest-api/" title="WP REST API" rel="ugc">WP REST API</a>.
This plugin is based on the work from<a href="https://github.com/PanManAms/WP-JSON-API-ACF" title="Panman on Github" rel="nofollow ugc">Panman on Github</a>. He was right when he said it would be better as plugin, but it would be even better if it would be available through the WordPress Plugin Repository.
An addition made to this plugin is that each ACF Field van be filtered throug the hook: JSON_META_ACFFIELDNAME (where ACFFIELDNAME depends on the fieldname you’ve added in the Advanced Custom Fields backend.)

WP REST API Custom Fields

The plugin is installed but nothing is in the output of API

JUst does not work

Shows Advanced Custom Field output to the WP REST API for posts, pages, taxonomies and users.

Eric Stout

A WordPress plugin that serves up slimmer WP Rest API endpoints, with some great 
enhancements like ACF fields, WordPress menu endpoints, and more. You can 
view the full documentation and features <a href="https://github.com/factor1/better-rest-endpoints" rel="nofollow ugc">here</a>.

Better Rest Endpoints

A WordPress plugin that serves up slimmer WP Rest API endpoints.

WP REST API Custom Fields vs Better Rest Endpoints