Private WP will make sure people can only read your blog after they log in. Already logged in users will see no difference. 
Users who are logged out will get the login page, and only that.
Use this for private “intranet style” blogs, or closed community sites.
Note that the plugin offers no options. Activate it to turn it on, deactivate it to turn it off!
If you also use Windows Live Writer, be sure to check out <a href="https://wordpress.org/extend/plugins/wlw-login/" rel="ugc">WLW Login</a>.

Private WP

This plugin is simple and robust (it works even it hasn't been updated for 2 years) ... yet it does exactly what it should do: lock the whole site with the login site.
For most of our beta sites this is exactly what we need while the clients editing the site until it is ready for golive. No unnecessary additional features that need your focus ... just active it and its runs.



Does what it should do

Makes your blog accessible only to logged in users.

This plugin allows you to easily open and close your website and display a custom message or HTML page when closed.
<ul>
<li>Simple yes/no toggle to open/close your website.</li>
<li>Display your own closed.php within your theme.</li>
<li>Display your own custom HTML markup, pasted directly into the plugin settings.</li>
<li>Display a basic message informing your visitors that your website is closed.</li>
<li>Set paths which bypass the closed page entirely.</li>
<li>Set a bypass GET parameter which will allow anyone you give the URL to to browse the website as normal while the site is closed.</li>
<li>Automatically clears any caches for W3 Total Cache and WP Super Cache.</li>
</ul>

Website Open/Closed Toggle

This plugin allows you to easily open and close your website and display a custom message or HTML page when closed.

Private WP vs Website Open/Closed Toggle