Google Sign-In - Google Sign-In is a secure authentication system that enables users to sign in with their Google accounts.
Keygen - A dead-simple software licensing API built for developers
uLogin - uLogin is a convenient service to login via social networks.
Labs64 NetLicensing - Monetize your digital products and services
Facebook Login - Facebook Login is a secure, fast and convenient way for people to log into your app or website.
LicenseSpring - Reliable and easy to use License-As-A-Service (LaaS) for for any software application