Universal 2nd Factor (U2F) is an open authentication standard that strengthens and simplifies two-factor authentication using specialized USB or NFC devices. U2F enables Internet users to securely access any number of online services, with one single device, instantly and with no drivers or client software needed.
Security Assertion Markup Language 2.0 (SAML 2.0) is a version of the SAML OASIS standard for exchanging authentication and authorization data between security domains.
OAuth 2.0 is the next evolution of the OAuth protocol which provides a method for clients to access server resources on behalf of a resource owner.
The System for Cross-domain Identity Management (SCIM) specification is designed to make managing user identities in cloud-based applications and services easier.