ahmedimraan

This plugin adds Custom Fields to WP REST API JSON output. Works with Advanced Custom Fields. 
Its as simple as Installing and Activating, once activated you can see an object named metadata.

WP REST API POST/ PAGE CUSTOM FIELDS

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

Daniel Bachhuber

Ryan McCue

Jonny Harris

Joe Hoyle

Rachel Baker

This plugin uses the OAuth 1.0a protocol to allow delegated authorization; that is, to allow applications to access a site using a set of secondary credentials. This allows server administrators to control which applications can access the site, as well as allowing users to control which applications have access to their data.
This plugin only supports WordPress >= 4.4.
The latest stable version is also available from the <a href="https://wordpress.org/plugins/rest-api-oauth1/" rel="ugc">WordPress Plugin Directory</a>.
<h3>New to OAuth</h3>
We strongly recommend you use an existing OAuth library. You’ll be best off if you understand the authorization process, but leave the actual implementation to well-tested libraries, as there are a lot of edge cases.
Start reading from <a href="docs/introduction/README.md" rel="nofollow ugc">the Introduction</a> to get started!
<h3>For OAuth Veterans</h3>
If you already know how to use OAuth, here’s the lowdown:
<ul>
<li>The plugin uses OAuth 1.0a in</li>
<li>We use the three-legged flow</li>
<li>To find the REST API index, apply the <a href="http://v2.wp-api.org/guide/discovery/" rel="nofollow ugc">API autodiscovery process</a></li>
<li>The endpoints for the OAuth process are available in the REST API index: check for <code>$.authentication.oauth1</code> in the index data.
<ul>
<li>The temporary credentials (request token) endpoint is <code>$.authentication.oauth1.request</code> (typically <code>/oauth1/request</code>)</li>
<li>The authorization endpoint is <code>$.authentication.oauth1.authorize</code> (typically <code>/oauth1/authorize</code>)</li>
<li>The token exchange (access token) endpoint is <code>$.authentication.oauth1.access</code> (typically <code>/oauth1/access</code>)</li>
</ul>
</li>
<li>Your callback URL must match the registered callback URL for the application in the scheme, authority (user/password) host, port, and path sections. (Subpaths are not allowed.)</li>
<li>The only signature method supported is HMAC-SHA1.</li>
<li>OAuth parameters are supported in the Authorization header, query (GET) parameters, or request body (POST) parameters (if encoded as <code>application/x-www-form-urlencoded</code>). OAuth parameters are not supported in JSON data.</li>
</ul>

WP REST API – OAuth 1.0a Server

Hello, I have made an adapter for Parse Server under Node.js with which you can link the login of any installation of wordpress in Parse Server, for that I have used your plugin, which is the one that gives us access_token and allows us to verify the authenticity Of the user registered in the server.

https://github.com/enriquecerda/parse-server-wordpress-login

Links with Parse-server Node.js

Got this working after some good amount of work! Thanks for bringing this and making API calls secure.

Worked like a charm!

Really Useful And Good Plugin
But Please
1- Reply on The Support Forum
2- Update it To Work Good With Last WordPress Verison
3 – No Clear Docs
4 - not work with localhost

Good But

Connect applications to your WordPress site without ever giving away your password.

WP REST API POST/ PAGE CUSTOM FIELDS vs WP REST API – OAuth 1.0a Server