System Design AI

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4. Design a Notification System
Deliver email, push and SMS with preferences, retries and honest delivery status.
ClassicMedium
Queues Streaming Distributed systems
+10
AWS Delivery semantics Fan out Kafka Notifications Real time Reliability Retries Amazon SQS User preferences
Worked design
Practice
33. Idempotency Keys
Any request can time out after the server has already acted. The client cannot tell that from a request that never arrived, and the only safe response to uncertainty is to retry — which, without help, charges the card twice.
Product & backendMedium
Exactly once Idempotency Payments
+2
Reliability Retries
Worked design
Practice
101. Design a Webhook Delivery System
Signed HTTPS callbacks for a billion events a day, at least once, retried for three days, with no endpoint able to slow another.
ClassicMedium
Queues Streaming Distributed systems
+8
At least once AWS Infrastructure Kafka Reliability Retries Amazon SQS Webhooks
Worked design
Practice

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