But once you move from a few hundred users to millions, things get tricky. Really tricky. It’s like trying to shout across a small room vs. trying to make yourself heard in a packed football stadium.
Let’s break down the challenges, the architecture, and how to build a system that can handle millions of personalized notifications — without blowing up your backend.
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🧩 1. The Problem
Imagine you’re building a health & wellness app.
Sarah needs a “Take your Paracetamol 💊 at 8 AM” reminder.
Raj needs an “Insulin shot 💉” ping.
Emily wants a “Workout warm-up 🏋️♀️” nudge.
At 8 AM sharp, millions of notifications need to go out.
What could go wrong?
Scalability issues: Looping over millions of device tokens = 🔥 backend meltdown.
Delivery problems: What if Sarah’s phone is offline? Or Raj’s app is force-closed?
