You’re in a backend interview. They ask: “How would you design a notification system (email, SMS, push) that scales?” Here’s how to approach it:
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Start with the requirements: - Support multiple channels (email, SMS, push). - Handle high throughput (millions of notifications). - Guarantee delivery as much as possible. - Allow retries and user-level preferences.
High-level design: - API layer → receives notification requests. - Queue → decouples producers from workers. - Workers → process notifications per channel. - Channel providers → (SES, Twilio, FCM).
Why a queue? - Spikes in traffic won’t overwhelm workers. - Enables retries on failure. - Supports backpressure if a downstream provider is slow.
Workers: - Each channel gets its own worker pool. - Workers must be idempotent → if retried, don’t double-send. - Use exponential backoff for retries.
Scaling: - Add more workers per channel when load increases. - Partition jobs across queues (per region or per channel). - Use rate limiting to respect provider quotas.
User preferences: - Store in DB: when, how, and what type of notifications users want. - Check before enqueueing a job. - Avoid wasting resources sending unwanted notifications.
Reliability concerns: - Dead-letter queues for jobs that keep failing. - Monitoring for provider outages. - Failover: switch providers (e.g., from Twilio → Nexmo) when needed.
How to frame it in an interview: “I’d design a notification service with an API, queue, channel-specific workers, retries, and provider failover. It would scale horizontally and respect user preferences while ensuring reliable delivery.”
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@Kaperskyguru good one
@Kaperskyguru I use Resend for this. Very straightforward.
@Kaperskyguru Nice read 🍻🙌
Got my 250k USD remote offer finally.
September Goals: ⚔️ - Complete Linear Algebra. - Complete Probability. - Complete Statistics. - Complete Machine Learning. - Complete Python. - Complete DBMS.
30 Blogs to Learn 30 System Design Concepts: 1. APIs: https://blog.algomaster.io/p/w... 2. API Gateways: https://blog.algomaster.io/p/w... 3. JWTs: https://blog.algomaster.io/p/j... 4. Webhooks: https://blog.algomaster.io/p/w... 5. REST vs GraphQL: https://blog.algomaster.io/p/r... 6. Load Balancing:
wasn't able to sleep last night, so completed kubernetes, from start to finish.
