Jordan Hlebarov

Frontend Gatekeeper hides the public frontend of your WordPress site unless visitors arrive with a configured URL parameter and value. It is useful for staging sites, soft launches, client previews, and pre-release content where you want to share a single shareable link instead of issuing individual user accounts.
Logged-in users always see the site normally, so editors and administrators are never blocked.
<h4>Features</h4>
<ul>
<li>Hide the entire public frontend with a single toggle.</li>
<li>Configurable parameter name and secret value, set per site.</li>
<li>Custom blocked message shown to unauthorized visitors (served with a 404 status).</li>
<li>Same-site link propagation: WordPress-generated links, menus, and block content automatically carry the access parameter forward, so visitors stay authorized while browsing.</li>
<li>Footer-script fallback that adds the parameter to links and forms rendered outside normal WordPress filters.</li>
<li>Gutenberg and block-theme aware through the <code>render_block</code> filter and <code>WP_HTML_Tag_Processor</code> when available.</li>
<li>Multisite-aware URL scoping for subdomain and subdirectory networks: access on <code>/site-a/</code> will not leak the token to <code>/site-b/</code>.</li>
<li>Logged-in users, wp-admin, REST API, AJAX, cron, and <code>wp-login.php</code> are always allowed through.</li>
</ul>
<h4>Typical use cases</h4>
<ul>
<li>Sharing a staging or pre-launch site with clients and stakeholders.</li>
<li>Gating a soft launch behind a single link instead of provisioning accounts.</li>
<li>Hiding draft or campaign content until you are ready to publish.</li>
</ul>

Frontend Gatekeeper

Hide the public WordPress frontend behind a secret URL parameter. Anyone with the link gets in; everyone else sees a 404.

turtlepod

<a href="http://genbu.me/plugins/fx-ssl/" rel="nofollow ugc">f(x) SSL</a> is a very simple plugin to force your site to use HTTPS.
After installation of this plugin, you can enable this in “Settings > General” under “SSL (HTTPS)” Section.
Features:
<ol>
<li>Super simple and easy to use. Only one checkbox.</li>
<li>Clear installation instruction.</li>
<li>Integrate to the WordPress “General” Settings seamlessly.</li>
<li>Fix URL in content, widget, etc to use HTTPS to make sure all images, etc loaded properly.</li>
<li>The GPL v2.0 or later license. 🙂 Use it to make something cool.</li>
<li>Support available at <a href="https://genbu.me/contact-us/" rel="nofollow ugc">Genbu Media</a>. 
Notes for developer: </li>
</ol>
<h4>Github</h4>
Development of this plugin is hosted at <a href="https://github.com/turtlepod/fx-ssl" rel="nofollow ugc">GitHub</a>. Pull request and bug reports are welcome.
<h4>Options</h4>
This plugin save the options in single option name: <code>fx-ssl</code>.
<h4>Hooks</h4>
List of hooks available in this plugin:
filter: <code>fx_ssl_notice_fail</code> (string)
Plugin activation notice if feature is not supported.
filter: <code>fx_ssl_notice_success</code> (string)
Plugin activation notice if feature is supported.
filter: <code>fx_ssl_notice_active</code> (string)
Plugin activation notice if feature is supported and already active.
filter: <code>fx_ssl_settings_section_description</code> (string)
Settings description.
filter: <code>fx_ssl_fix_url</code> (string)
If you need to pass other URL to parse to content, excerpt, text widget, etc.

Frontend Gatekeeper vs f(x) SSL