A million taps a second. One tiny message.
25 million people tapping 🔥 at the same moment — and not one of those taps is ever delivered to anyone.
What you'll learn
- The live-reactions use case in four steps — what the app actually owes every viewer
- Why sending every reaction to every viewer is impossible, in one line of maths
- The five Azure services that count instead — Front Door, Container Apps, Event Hubs, Stream Analytics, Web PubSub
Share this passage
Drawing…
Understand it one step at a time
The short runs these in order in about 70 seconds. Here they are written out — pick any step to jump the short straight to it.
25 million people, one ball
25 million viewers, one final ball of the match. Watch the reactions land — this is a single second of live traffic, not the whole game.
Frequently asked questions
- Why can't you just broadcast every reaction tap to every viewer?
- The maths doesn't scale — a million viewers each tapping becomes a million events, and delivering each one to a million other viewers is a delivery count that grows with the square of the audience. What was supposed to be growth becomes the outage.
- How is a live reactions feature actually built at scale?
- Reactions are counted rather than individually delivered — Front Door, Container Apps, Event Hubs, Stream Analytics and Web PubSub each handle one stage (ingest, aggregate, fan-out), so viewers see an updating count instead of every raw tap.
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.
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