List Users in the API

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "VisualEditor0",
      "Effect": "Allow",
      "Action": "cognito-idp:ListUsers",
      "Resource": "arn:aws:cognito-idp:<your region>:<account id>:userpool/<user pool id>"
    }
  ]
}

import {CognitoIdentityProviderClient, paginateListUsers} from '@aws-sdk/client-cognito-identity-provider';

const cognito = new CognitoIdentityProviderClient({});

export const handler = async function () {
    const paginator = paginateListUsers({client: cognito}, {
        UserPoolId: '<user pool id>',
        AttributesToGet: [],
        Filter: '',
        Limit: 60
    });

    let logins = [];

    for await (const page of paginator) {
        for (const user of page.Users) {
            logins.push(user.Username);
        }
    }

    return logins;
};

{
  "type":"array",
  "items": {
    "type":"string"
  }
}