Anonymous URL Shortener - Anonymous URL Shortener, Referer, Anonymizer, Redirection service.
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.
Zapier URL Shortener - Zapier is an online platform that offers unique services related to URLs, including the shortening of URLs.
Short.io - Short.io makes short links (vanity urls) on your own domain. Free signup, analytics and API. Chrome, slack, zapier and segment integrations.
Lstu - A nice and open source url shortener. You can use it as service or install it on your own server.
Shlink - A self-hosted URL shortener