usernameConfiguration

Sets the case sensitivity option for sign-in usernames. When CaseSensitive is false (case insensitive), users can sign in with any combination of capital and lowercase letters. For example, username , USERNAME , or UserName , or for email, email@example.com or EMaiL@eXamplE.Com . For most use cases, set case sensitivity to false as a best practice. When usernames and email addresses are case insensitive, Amazon Cognito treats any variation in case as the same user, and prevents a case variation from being assigned to the same attribute for a different user. When CaseSensitive is true (case sensitive), Amazon Cognito interprets USERNAME and UserName as distinct users. This configuration is immutable after you set it.