Zack Tollman

When deploying a TLS enabled website, you must ensure that all content loaded on the site is loaded from secure origin. 
If your content is loaded from an insecure source, the security of your whole site is compromised and modern browsers 
will downgrade your website’s security rating.
The HTTPS Mixed Content Detector plugin attempts to identify sources of mixed content warnings. The plugin will examine 
content loaded from the site when admins are viewing the site. Any content that violates the policy of loading content 
that originates from “https:” resources will trigger an error and that resource will be logged. Viewing the log will 
allow you to examine the site for any warnings and remove them before they cause problems for your website.

HTTPS Mixed Content Detector

Super useful for sites transitioning to HTTPS

Detects and logs content that will cause mixed content warnings.

neoslab

Simple HTTPS automatically detects if your website run properly over HTTPS and fix your website accordingly without any extra useless line of code. Your website will move to SSL within few clicks. This plugin also allow you to enable HTTP Strict Transport Security for your website.
<h3>License</h3>
Good news, this plugin is free for everyone! Since it’s released under the GPL, you can use it free of charge on your personal or commercial site.

Simple HTTPS

Correct your SSL/HTTPS issue within few clicks and enable HTTP Strict Transport Security for your website.

HTTPS Mixed Content Detector vs Simple HTTPS