Shorten.REST - A URL shortener API you can depend on
Linkly - Linkly is a tool to help affiliate marketers track clicks and improve revenues.
Short.io - Short.io makes short links (vanity urls) on your own domain. Free signup, analytics and API. Chrome, slack, zapier and segment integrations.
RocketLink - Rocketlink helps to grow your audience with URL shortener that allows firing retargeting scripts when the link is clicked.
MergeURL - Shorten URLs for free without user registration.
Sniply - Sniply is a content marketing tool providing social media conversion.