To make this really easy, we’ve added a Notifications section to your dashboard. You enter a Slack webhook URL, and we’ll notify you every time a new user signs up. You can also set different webhooks for your test and production environments, to avoid the long list of fake notifications (test@mycompany.com, test2@mycompany.com, …).

If you are looking for more advanced actions on user signup or other events, you likely want webhooks.