NoPass.me - Open-source identity verification
Certificates by Graphy - Certificates by Graphy lets you share beautiful custom certificates to all your learners at once.
Amazon Cognito - Amazon Cognito lets you add user sign-up, sign-in, and access control to your web and mobile apps quickly and easily. It scales to millions of users and supports sign-in with social identity providers and enterprise identity providers via SAML 2.0.
Sertifier - Best way to send smart certificates & open badges!
Civic Token - Access to identity verification via the blockchain
CertifyMe - Your trusted credential platform