The Krypton app for iOS and Android allows you to connect your mobile devices with a web browser or other supported websites using the standard FIDO Universal 2nd Factor (U2F) protocol. The Krypton Authenticator is a companion extension for Krypton that works on desktop and mobile devices. It has a QR code scanner that can be scanned on the website to connect to the site's FIDO Universal 2nd Factor (U2F) implementation and securely login to the website.

The extension supports both the FIDO U2F-based (Universal 2nd Factor) and the WebAuthn (Open Authentication) U2F standards, and supports mobile and desktop versions of the app.

The Krypton app supports most websites with FIDO U2F support and is compatible with Android versions 5.0 and higher, iOS versions 6.0 and higher, and Windows versions 10 and higher.

It provides an easy, intuitive way to have your phone as an additional security factor to log in to your accounts and websites.