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.

tstephenson

My use case is to allow content authors to write help pages in WordPress. 
This content is fetched and embedded into a single page application hosted on another domain.
AJAX requests to this site from another are typically disallowed by the browser’s security model. 
To permit legitimate uses the requesting browser may include an Origin header containing its domain. 
This plugin uses the Origin header to decide whether to allow the request or not. 
Allowed domains can be specified in the plugin’s Settings page.

WP-CORS

Allows AJAX requests from other sites to integrate content from your site using the CORS standard.

WP REST API Custom Fields vs WP-CORS