Shorten.REST - A URL shortener API you can depend on
PixelMe - URL shortener for savvy marketers
Pixela - Record and Track your habits or effort. All by API.
Avoid Humans - Find empty cafes, bars & places nearby. Enjoy, introverts.
Cutt.ly - Free custom URL Shortener and branded URLs with advanced links tracking and Link Management Platform & API.
MergeURL - Shorten URLs for free without user registration.