BjornW

RESTless is a tiny WordPress plugin which disables access to the REST API (available in WordPress since version 4.4) for non-authenticated users. 
This prevents usage of the REST API by the general public and limits access to those with login credentials. No REST for the wicked.
It also supports WordPress Multisite installations.
<h3>Notes</h3>
Credits:
Sword icon used in the WordPress plugin repository and found as /assets/icon* 
From the series <a href="http://www.toicon.com/series/sketchy" rel="nofollow ugc">‘Sketchy’</a> By <a href="http://www.toicon.com/authors/1" rel="nofollow ugc">Shannon E Thomas</a>
Thanks Shannon E Thomas and to[icon] for sharing your work!
WordPress repository banner image found in /assets/banner*:
Orginal painting: <a href="http://hdl.handle.net/10934/RM0001.COLLECT.319230" rel="nofollow ugc">‘Draak’</a> 
Drawn by: <a href="https://en.wikipedia.org/wiki/Utagawa_Kuniyoshi" rel="nofollow ugc">Utagawa Kuniyoshi</a> 
Dated around 1808 – 1861 
Repository: Rijksmuseum.nl 
Modified by: <a href="https://burobjorn.nl" rel="nofollow ugc">Björn Wijers</a>
Thanks Rijksmuseum!

RESTless

RESTless disables REST calls for non-authenticated requests.

Pete Nelson

Allows tweaking of several REST API settings
<ul>
<li>Disable the REST API</li>
<li>Remove WordPress core endpoints</li>
<li>Require authentication for core endpoints</li>
<li>Force SSL</li>
<li>WP-CLI commands: wp rest-api-toolbox</li>
</ul>
Find us on GitHub at https://github.com/petenelson/wp-rest-api-toolbox
(Creative commons toolbox image provided by James Tworow https://www.flickr.com/photos/sherlock77/)

REST API Toolbox

Allows tweaking of several REST API settings

RESTless vs REST API Toolbox