YOUR BRIEF
What to work through
Work through a notification system as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- Send push, SMS and email notifications, triggered by services or scheduled jobs
- Users can opt out per channel
- Build notifications from reusable templates
- Support iOS, Android and desktop
BEFORE YOU START
Constraints to discuss
- Soft real time: fast normally, delays are fine under heavy load
- No notification is lost
- 10 million push, 1 million SMS and 5 million emails a day
- An outage at one provider does not stop the other channels
Need a starting point?
Watch for these common gaps as you prepare:
- One notification server that is a single point of failure
- Calling providers inline from the request with no queue
- Claiming exactly-once delivery
- Forgetting to check opt-outs before sending
- No retry path or monitoring of queue depth
Why this question is in the collection
These sources connect the problem to company interview reports or preparation guides. They do not guarantee what a company will ask you.