Designs

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All designs 10

Ordered by design number

Company tags are community-reported. Counts on cards show how many people reported that design.

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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
6. Design a News Feed
Build a paginated feed that handles high-fan-out authors, fresh posts and visibility changes.
ClassicMedium
Caching Databases Streaming
+11
Privacy Distributed systems AWS DynamoDB Fan out Kafka News feed Pagination Redis Social Timeline
Worked design
Practice
30. Transactional Outbox
A service commits to its database and then publishes an event. If it dies in between, the row exists and no one hears about it. Publishing first has the mirror problem: an event for a write that never happened. There is no ordering of two independent systems that makes this safe.
Product & backendMedium
Queues Streaming Transactions
+5
Distributed systems Change data capture Consistency Kafka Outbox
Worked design
Practice
44. Design a Price Tracking Service
Watch prices on 500 million products with a polite crawler and a million browsers, verify what you are told, and notify subscribers within minutes of a drop.
ClassicMedium
Databases Streaming Distributed systems
+6
AWS Crawling Crowdsourcing DynamoDB Kafka Notifications
Worked design
Practice
49. Design an Online Auction like eBay
Take bids on 10 million live auctions with one consistent highest bid, lose none, push the price to every watcher and end each auction fairly.
ClassicMedium
Streaming Concurrency Distributed systems
+7
Auctions Aurora AWS Contention Kafka Real time Server sent events
Worked design
Practice
52. Design a Payment System like Stripe
Charge cards through the networks exactly once: idempotency keys, a card vault, timeouts as unknowns, signed webhooks, a double-entry ledger and reconciliation. One-hour boards for junior, senior and staff, with the theory behind them.
ClassicMedium
Streaming Distributed systems AWS
+6
Idempotency Kafka Ledger Payments PCI compliance Reconciliation
Worked design
Practice
57. Design Post Search like Facebook
Search a billion posts a day by keyword, newest or most liked first, with an inverted index you build yourself.
ClassicMedium
Caching Databases Streaming
+7
Search Distributed systems AWS DynamoDB Inverted index Kafka Redis
Worked design
Practice
88. Design a Reviews and Ratings System
Dish reviews only from customers who ordered them, votes counted from a change stream, reviews ranked by the Wilson bound, payouts made exactly once.
ClassicMedium
Databases Streaming Distributed systems
+7
AWS DynamoDB Kafka Ranking Ratings Reviews Social
Worked design
Practice
93. Design a Real-Time Game Leaderboard
Rank 200 million players in real time with sharded Redis sorted sets, count every game exactly once, and close a season fairly.
ClassicMedium
Caching Databases Streaming
+8
Distributed systems AWS Flink Gaming Kafka Leaderboards Redis Sorted sets
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

Each design brings together the brief, practice, examples and discussion.

All designs 10

4. Design a Notification System

6. Design a News Feed

30. Transactional Outbox

44. Design a Price Tracking Service

49. Design an Online Auction like eBay

52. Design a Payment System like Stripe

57. Design Post Search like Facebook

88. Design a Reviews and Ratings System

93. Design a Real-Time Game Leaderboard

101. Design a Webhook Delivery System