Design
Notification Service
Design a multi-channel notification service that sends alerts via push, email, SMS, and in-app with user preference control.
01 - Why interviewers ask this
Multi-channel delivery (push/SMS/email) is a great test of the Strategy/Adapter pattern — interviewers want new channels to be addable without touching existing dispatch logic.
02 - Where this system exists in the real world
You interact with this design every day.
Push/SMS/email notification services (Twilio, SNS)
App engagement and re-engagement systems
Transactional alert systems (banking, delivery)
03 - What you'll master
Solve this once. Know it forever.
Apply Strategy/Adapter for multiple channels
Model user notification preferences
Handle delivery retries and failures
04 - What you'll design
8 functional · 3 non-functional requirements.
Send notifications through multiple channels: push, email, SMS, in-app
7 more requirements inside
Sign in to unlock the full brief and start designing
05 - Companies that ask this
You may face this exact question in your next interview.
Ready?
Open the canvas.
Design it yourself.
See all requirements, use staged hints, run your code, and compare with community discussions - all on the same canvas.
Start Solving