Design a Notifications and Alerts System (Email, SMS, Push)

Why This Matters

Your app is chatty. It wants to say “welcome,” “your order shipped,” “please update your card,” and occasionally “everything is on fire.” A well-designed notifications and alerts system makes those messages timely, reliable, and respectful of users’ preferences—without waking anyone at 3 a.m.

Think of it as a mailroom for your product: it routes the right message to the right person through the right channel (Email, SMS, Push), at the right time, with retries, tracking, and receipts. Do it well, and users trust you. Do it poorly, and they block you. Or worse, churn.