System Design · Senior · Question 40 of 75
How would you design a notification system (email, push, in-app)?
- ✓Correct answer: Queue, user preferences, deduplication, retries
- 2Send the notification synchronously right from the HTTP request handler
- 3Store notifications only in the recipient's
localStorage
Explanation
An event goes into a queue; the notification service checks preferences and quiet hours, picks channels, groups and deduplicates, and sends via providers with retries and rate limits. In-app notifications are stored on the server and delivered via SSE/WebSocket.