You can use your API key from Daily.co together with Zapier to get notified when someone joins one of your rooms, which is helpful in scenarios like private or team-only rooms, reminders, or locking specific rooms. To create this notification, you'll need a Daily.co account and a Zapier account, and follow these steps: first, sign in to Zapier, then choose the "Catch Hook" trigger event, set up your webhook URL with your Daily.co API key and room link, open your meeting link, test and continue, add an optional filter for notifications from other users, add an action step like sending a direct message to Slack, and finally save your Zap.