Migrate Firebase auth users from one GCP project to another

migrate-firebase-auth-users.js

import { identitytoolkit } from "@googleapis/identitytoolkit";

const { relyingparty } = identitytoolkit({
  version: "v3",
});

let nextPageToken = undefined;

do {
  const res = await relyingparty.downloadAccount({
    requestBody: {
      targetProjectId: "project-id",
      nextPageToken,
    },
  });
  
  nextPageToken = res.data.nextPageToken;

  await relyingparty.uploadAccount({
    requestBody: {
      targetProjectId: "project-id",
      users: res.data.users,
    }
  })
} while (nextPageToken);