No setup required! You only need an SSL certificate, and this plugin will do the rest.
Clean up WordPress website HTTPS insecure content
A fix for mixed content! This Plugin removes HTTP and HTTPS protocols from all links. Works in Front- and Backend!
Fixes all mixed content warnings. Removes both HTTP and HTTPS protocols from all links from the front-end and back-end.
Force http/https for resources, depending on the scheme you use.
This plugin removes the http/https schema from urls inside the blog source code and replace them with double slash.