chl.li URL shortener - A simple, modern, free and privacy-friendly 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.
Short.io - Short.io makes short links (vanity urls) on your own domain. Free signup, analytics and API. Chrome, slack, zapier and segment integrations.
Ow.ly - Shorten links, measure traffic, and demonstrate social ROI right inside the Hootsuite dashboard.
PixelMe - URL shortener for savvy marketers
Polr - An open source URL shortener. A great non-profit and free alternative to bit.ly, TinyURL, or goo.gl.