System Design made easy

Small interactive worlds that show how real systems stay fast. Break one, then fix it.

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A peek inside

A few of the worlds so far, each built around one idea.

The living room at night: a penguin on the sofa watching reels on a giant phone-shaped TV, a cat asleep beside them

Caching

Why the next reel is already waiting. A penguin doomscrolls, and without a cache every swipe means a wait.

 The Krill Grill, a takeaway on a street corner, with penguins queueing at its windows

Load balancing and rate limiting

The Krill Grill at rush hour. One chef drowns in orders while the others stand idle, until someone shares out the work.

 The Emperor hotel: a lobby with a front desk and a queue, and the kitchen, office, linen room and store behind

Reverse proxy

The Emperor hotel. Guests barge into the back of house, until a front desk answers for every room.

Watch it break, then fix it

Each world opens on the problem. Flip the switch to add the fix, and the penguins show you what changed.

A short panel beside each world explains the real system underneath in plain English, with a few real numbers and links to go deeper.

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