oishikazuo

Self Shortener is a WordPress plugin to be able to handle URL shortening 
feature, by your WordPress site itself.
Self Shortener can:
<ul>
<li>create short URL using your site URL.</li>
<li>generate random short URL key, by specifying key length.</li>
<li>specify fix URL key instead of random generating.</li>
<li>handle I18N message. Currenly supports English and Japanese.</li>
</ul>
See http://giraffy.jp/products_en/wordpress/selfshortener/ . 
(In Japanese, http://giraffy.jp/products/wordpress/selfshortener/ )

Self Shortener

URL Shortener handled by your WordPress site itself.

Julio Potier

Grégory Viguier

SecuPress

This plugin forbids access to https://example.com/wp-login.php and creates new urls, like https://example.com/login or https://example.com/logout. 
This is a great way to limit bots trying to brute-force your login (trying to guess your login and password). Of course, the new URLs are easier to remember too.
Also remember: the use of this plugin does NOT exempt you to use a strong password. Moreover, never use “admin” as login, this is the first attempt for bots.
By the way, if you are looking for a complete security solution, take a look at <a href="https://wordpress.org/plugins/secupress/" rel="ugc">SecuPress</a>: Move Login is included inside.
<h4>Multisite</h4>
Yes! The plugin must be activated from your network. 
Note 1: this plugin deals only with <code>wp-login.php</code>, not with <code>wp-signup.php</code> nor with <code>wp-activate.php</code> (yet). That means https://example.com/register will still redirect to https://example.com/wp-signup.php. I think this will be the next step though, but no ETA. 
Note 2: if users/sites registrations are open, you shouldn’t use this plugin yet. There are some places where the log in address is hard coded and not filterable. A <a href="https://core.trac.wordpress.org/ticket/31495" title="Always use 'login' as $scheme parameter for "login-ish" URLs, and other inconsistencies" rel="nofollow ugc">bug ticket</a> is open.
<h4>Requirements</h4>
<ul>
<li>You will need a FTP access: if the <code>.htaccess</code>/<code>web.config</code> file is not writable (you will need to add the given rules manually), or if something is wrong and you can’t log in anymore (see the FAQ in that case).</li>
<li>Should work on IIS7+ servers but not tested (I guess you should probably save a copy of your <code>web.config</code> file before the plugin activation).</li>
<li>For Nginx servers, the rewrite rules are not written automatically of course, but they are provided as information in the plugin settings page.</li>
</ul>

Move Login

Don't know why I didn't find "Move Login" first. I already tested 2 alternative free plugins and it was deficient in different ways.  "Move Login" is powerful, light and easy to set up. Very nice find. Thanks.

The best of the 3 ones I tested

Change your login URL for something like https://example.com/login and stop login brute-force attempts.

Self Shortener vs Move Login