Azure

1.6 million downloads. One photo.

A flash sale turns the API into a file server.

What you'll learn

Why a flash sale sends the same image bytes from one server to every phone
How a CDN like Azure Front Door serves files from an edge location near each user
What never goes on a CDN, and why a changed image needs a new URL

Azure 10 steps 58 seconds September 28, 2026 —

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Understand it one step at a time

The short runs these in order in about 58 seconds. Here they are written out — pick any step to jump the short straight to it.

1 Step 1 of 10

One photo, 400,000 phones

Four photos per page, 350 KB each. Everybody opens the page at 12:00.

Free app · no app store

These are built for a phone

Every short is drawn at full portrait height, the shape a phone already is. Installed, it opens full-bleed with no address bar across the top — and the whole library reads offline.

Read deeper on Azure

Twenty seconds gets the shape of an idea across. These go into how it behaves in production.

The Flash Sale That Ran Out of Bandwidth: When to Use a CDN on Azure

When to use a CDN on Azure, from a flash sale where one App Service served 1.6 million photo downloads. What to cache, and what never to.
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A script tries 8,000 passwords a minute against your login API at 3am. Rate limiting, smart lockout and Defender for Cloud make speed the losing move.
Azure Key Vault Explained: The One Secret Tutorials Never Remove

Moving every secret into Key Vault leaves exactly one behind: the credential that opens the vault. A managed identity is what removes it.

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