What is a custom URL shortener? and why use one?
You’ve almost certainly seen shortened URLs before. They’re all over the Web, and their use is particularly noticeable on social networks and sites that have character limits on posts (e.g., Twitter). These short URLs are created via URL shorteners. Essentially, a URL shortener takes a long URL (e.g., http://coreyjmahler.com/topics/setting-up-a-wordpress-multisite-install-to-use-multiple-domains/) and turns it into a much shorter URL (e.g., http://wp.me/P2WnDd-3E). The shorter URL is much easier to remember (and some URL shorteners allow the bit after the “/” to be customized for even easier memorization) and takes up many fewer characters (helpful on sites that limit the number of characters a post can contain).
There are literally hundreds of URL shorteners available. Some are large names (e.g., Google [goo.gl] and bitly [bit.ly]), and others are small or serve particular niches. Of course, there are also ways to create and to operate your own; perhaps the most prominent example of a self-hosted URL shortener is YOURLS.
Which one to use?
Which URL shortener you will want to use depends largely on your needs. If you’re shortening URLs for a business, you will likely have different requirements from someone who is simply shortening links to post them on Twitter. A large business that relies on Web marketing and posts hundreds of links a day may want to opt for a paid service, while a smaller business may find free alternatives more suitable.
For quick URL shortening (including basic analytics), is.gd is a great option. It has one of the shortest domains available (a mere five characters including the period), and is reliable and free. For companies that post hundreds of links and require advance analytics, bitly is probably the best option, but its enhanced functionality doesn’t come cheap. If you want to host your own URL shortener (which gives you greater control), the best option currently available is YOURLS. All you need for YOURLS is a directory in which to drop its files and a database in which it can store its information.