Polr - An open source URL shortener. A great non-profit and free alternative to bit.ly, TinyURL, or goo.gl.
Akari Link Shortener - Anime-themed URL shortener.
YOURLS - YOURLS is a website that contains all the tools you need to create and launch your very own URL shortener. URL shorteners like bitly or TinyURL are fine for public use, but they offer limited options in terms of URL customization.
Bitly - Get the most out of your social and online marketing efforts. Own, understand and activate your best audience through the power of the link with Bitly Enterprise.
Framalink - Free Open-source URL Shortening application
Shlink - A self-hosted URL shortener