The default WordPress “shortlink” URLs look like this: <code>http://www.example.com/blog/?p=123</code>, where “<code>123</code>” is actually a 7+ digit decimal number. This plugin shrinks your shortlinks by encoding that number into only 4 characters, and using the abbreviated URL prefix of your choice.
On my site, the default shortlinks are 35 bytes long, even though I have a very short domain name. This plugin shrinks them to 21 total bytes, which is comparable to most public URL-shortener services, and better than many.
E.g., this: <code>http://www.jwz.org/blog/?p=13240780</code> 
becomes: <code>http://jwz.org/b/ygnM</code>
This doesn’t affect your (long) permalinks: those can still be in whatever format you like.

Base64 Shortlinks

This plugin makes your shortlinks shorter!

Dipakkumar Parmar

Naresh Parmar

Link Shortner helps you generate short links and share any URL on or off your WordPress website. 
With this plugin, you can:
<ul>
<li>Create short links for posts.</li>
<li>Share short links on social media, emails, or anywhere online.</li>
<li>Quickly regenerate links with one click from your WordPress admin.</li>
</ul>
Whether you’re managing content, marketing campaigns, or just want neat and professional URLs, Link Shortner makes it simple and effective.

Link Shortner

Easy to use

Link Shortner allows you to easily create clean, branded short permalink links for your posts custom URL.

Base64 Shortlinks vs Link Shortner