Which design type is this question?

It is a backend system question. You design a notification system and explain your choices the way you would in an interview.

Is this question asked at entry level?

It is marked Hard. It suits engineers preparing for senior interviews, where you are expected to drive the discussion and go deep on trade-offs.

What should I cover first?

Start with the requirements: what the system must do, how well it must do it and which numbers change the design. Agree on scope with the interviewer before you design anything.

Can I practise it for free?

Yes. It is one of the free questions. Sign up to practise it step by step. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.

Design a notification system

FreeBackend systemHard

Notifications
Real time
Scalability

Quick answer

This backend system interview question asks you to design a notification system. Aim for a design that meets its requirements at the stated scale, then explain its main components, data flow and trade-offs. Interviewers want to see how you scope the problem, size it and defend each choice.

The problem

Designing a Notification System involves building a scalable, reliable service that delivers real-time notifications across multiple channels, including Push, SMS, Email, and Webhooks. The system must handle high throughput, retries, rate limiting, and user preferences, ensuring low latency and fault tolerance.

Key concepts

Notifications
Real time
Scalability
Third party integration

How you’ll practise

6 short steps · save and come back any time

Requirements
Estimate
API and data
High-level design
Deep dives
Wrap-up

Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.

What do interviewers look for?

In any backend system design round.

Clarifies the requirements before drawing anything
Uses a few numbers that actually change the design
Draws a clear path from the client to storage
Picks storage and caching with reasons, not by habit
Explains what breaks first under load and how to fix it
States trade-offs openly instead of claiming a perfect design

Questions people ask about this interview question

Which design type is this question?: It is a backend system question. You design a notification system and explain your choices the way you would in an interview.
Is this question asked at entry level?: It is marked Hard. It suits engineers preparing for senior interviews, where you are expected to drive the discussion and go deep on trade-offs.
What should I cover first?: Start with the requirements: what the system must do, how well it must do it and which numbers change the design. Agree on scope with the interviewer before you design anything.
Can I practise it for free?: Yes. It is one of the free questions. Sign up to practise it step by step. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.

The problem

Key concepts

How you’ll practise

What do interviewers look for?

Questions people ask about this interview question

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