chingor13

This plugin enables a resourceful REST interface for posts and comments. Authentication is handled via the <a href="https://wordpress.org/extend/plugins/oauth-provider/" rel="ugc">oauth-provider plugin</a>.
For more information about resourceful routing, see <a href="http://guides.rubyonrails.org/routing.html" rel="nofollow ugc">here</a>.
Acceptable return formats:
<ul>
<li>JSON</li>
</ul>
Endpoints:
<ul>
<li>GET – /api/posts.:format</li>
<li>GET – /api/posts/:id.:format</li>
<li>POST – /api/posts.:format</li>
<li>PUT – /api/posts/:id.:format</li>
<li>GET – /api/comments.:format</li>
<li>GET – /api/comments/:id.:format</li>
<li>POST – /api/comments.:format</li>
<li>PUT – /api/comments/:id.:format</li>
</ul>
<h3>To Do</h3>
<ol>
<li>Limit authentication to specific endpoints (customizable)</li>
</ol>

OAuthRest

OAuthRest is an implementation of a resourceful REST api.  It uses authentication via the oauth-provider plugin.

Matthias Pfefferle

David Shanske

IndieWeb

The plugin turns WordPress into an IndieAuth endpoint. This can be used to act as an authentication mechanism for WordPress and its REST API, as well as an identity mechanism for other sites. It uses the URL from the profile page to identify the blog user or your author url. We recommend your site be served over https to use this. 
 measure then updates must be made.You can also install this plugin to enable web sign-in for your site using your domain.

IndieAuth

Works perfectly! Guides you on how to setup your .htaccess too.

Easy to setup

IndieAuth is a way to allow users to use their own domain to sign into other websites and services.

OAuthRest vs IndieAuth