A filter string of the form "AttributeName Filter-Type "AttributeValue"". Quotation marks within the filter string must be escaped using the backslash (\) character. For example, "family_name = \"Reddy\"".

AttributeName: The name of the attribute to search for. You can only search for one attribute at a time.
Filter-Type: For an exact match, use =, for example, "given_name = \"Jon\"". For a prefix ("starts with") match, use ^=, for example, "given_name ^= \"Jon\"".
AttributeValue: The attribute value that must be matched for each user.

If the filter string is empty, ListUsers returns all users in the user pool.

You can only search for the following standard attributes:

username (case-sensitive)
email
phone_number
name
given_name
family_name
preferred_username
cognito:user_status (called Enabled in the Console) (case-sensitive)
status (case-insensitive)

Custom attributes are not searchable.

For more information, see Searching for Users Using the ListUsers API and Examples of Using the ListUsers API in the Amazon Cognito Developer Guide.

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