Passport!

LoginRadius’ Customer Identity and Access Management (cIAM) platform helps companies deliver a connected customer experience by streamlining the registration and login processes for their web,mobile, and other digital properties. Organizations can increase registrations, improve customer experience, consolidate customer data, and leverage customer profiles to increase revenue through targeted and personalized marketing campaigns.

You can connect any application (written in any language or on any stack) to Auth0 and define its Connection, the method used to authenticate the users of that application:

OneLogin is a cloud-based IAM solution providing users secure access to cloud applications from any device.

Provide secure identity management and single sign-on to any application, whether in the cloud, on-premises or on a mobile device for your employees, partners and customers with Okta.

Gigya is one of the leading social choice for websites, integrating online businesses with the top social networks such as Facebook, Twitter and LinkedIn and consolidating the most powerful social features in a single solution.

Powerful authentication, authorization, and user management for any application

Open Source Modular User Accounts Library for Node.js built on top of Passport.js