It's Amazon Great Indian Sale. Midnight strikes. Millions of people hit refresh simultaneously.

Your internet slows down. The app feels laggy. You're frantically trying to add that phone to your cart before it goes out of stock.

And somehow Amazon doesn't crash.

Millions of orders. Milliseconds apart. Payments processing. Inventory updating. Warehouses getting notified. Delivery partners being assigned.

All at once.

How does any system survive that?

Here's the engineering behind it.

The Scale That Will Surprise You

Amazon Prime Day 2024 over 200 million items sold in 48 hours.

That's roughly 1.4 million items per minute. 23,000 items per second. At peak.

Each item involves:

Checking inventory

Processing payment

Updating stock count

Notifying the warehouse

Scheduling delivery

Sending confirmation email

Updating the seller dashboard

Multiply that by 23,000 every second.

This is not a website problem.…