List of free shortener stuff for developerππ½
If you're looking for all programming tools around shortener (not just free). Check this page List of shortener Programming Tools

Cuttly
Free custom URL Shortener and branded URLs with advanced links tracking and Link Management Platform & API. Shorten and replace long URL to short link. Track your links. Use it to affiliate programs, ads, social websites, emails, text messages, flyers with QR code.
Tag: api, shortener, url
Branded domains up to 3 Link analytics history last 30 days API rate limit 6 calls / 60 sec