AWS Cognito supports:
You can create your own user directory within Amazon Cognito, or you can authenticate users through Social Identity Providers such as Facebook, Twitter, or Amazon; with SAML identity solutions; or by using your own identity system. In addition, AWS Cognito enables you to save data locally on users' devices, allowing your applications to work even when the devices are offline.
You can then synchronize data across users' devices so that their app experience remains consistent regardless of the device they use.