Byepass is an authentication platform that replaces passwords, authenticating users against their email address. Byepass acts like a cross site/app session, without requiring users to register to, or download any 3rd-party apps, completely backwards compatible with all existing email/password logins, and easy enough for your Nanny to use if she needs to order her groceries online.
API available for integration with every website/app, wordpress plugin available for one click install to wordpress.