Patryk

Force protocol relative (\ instead http:\ or https:\) for files added in the content editor (eg. post, page)
Before, when add media:
<pre><code><a href="https://wordpress.org/wp-content/uploads/some-cool-photo.png"><img src="https://wordpress.org/wp-content/uploads/some-cool-photo.png" alt="Some cool photo" width="1920" height="1410" class="aligncenter size-full wp-image-19200813" /></a>
</code></pre>
After, when add media:
<pre><code><a href="//wordpress.org/wp-content/uploads/some-cool-photo.png"><img src="https://wordpress.org/wp-content/uploads/some-cool-photo.png" alt="Some cool photo" width="1920" height="1410" class="aligncenter size-full wp-image-19200813" /></a>
</code></pre>
The plugin works only for newly added media (does not change the older entries).

PRyC WP: Force protocol relative to uploaded media

Force protocol relative (\ instead http:\ or https:\) for files added in the content editor (eg. post, page)

David Gregg

CCS-HTTPS is a simple plugin that allows you to identify which pages should have HTTPS enforced. All other pages will have HTTP enforced. 
This plug-in will not interfere with or override any of the built-in WordPress options related to forcing HTTPS for the login and admin pages.

CCS-HTTPS

A simple plugin that allows you to identify which pages should have HTTPS enforced. All other pages will have HTTP enforced.

PRyC WP: Force protocol relative to uploaded media vs CCS-HTTPS