Logging in with SPRESSO is simple: after entering your email address, you are prompted to enter your password at your email provider. No registration process! Instead, you stay on the same web page all the time.
SPRESSO is the only web single sign-on system which provides privacy: although your email provider testifies for your identity, it does not learn where you log in.
The security and privacy of SPRESSO have been proven using formal methods. Identity providers can support two-factor authentication to further strengthen the security.
Any email provider can serve as an identity provider in SPRESSO, and any web site can integrate Login with SPRESSO. There is no setup or registration required. SPRESSO is decentralized: It does not rely on a central authority.
SPRESSO works on any modern browser and device that supports HTML5. There is no need to install and maintain any software or browser extensions.