Guided practice

Start with a template. Work through each step. Ask Coach when you need a second opinion.

All designs

Classic designs 6

Ordered by design number

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

SecurityClear filters

5. Design a Chat System
Send durable messages, reconnect devices and explain ordering and delivery receipts.
ClassicMedium
Databases Security Privacy
+11
Distributed systems AWS Chat DynamoDB End to end encryption Messaging Multi region Offline first Ordering Redis Pub/Sub WebSockets
Worked design
Practice
7. Design a File Storage Service
Upload and share large files with resumable transfer, versions and safe metadata changes.
ClassicMedium
Databases Object storage Security
+9
AWS Deduplication DynamoDB File sync Large files Multipart upload Permissions Versioning WebSockets
Worked design
Practice
10. Design an API Gateway
Route API traffic with authentication, tenant limits and safe configuration rollout.
ClassicMedium
Security API design API gateways
+7
Authentication AWS Control plane Envoy Rate limiting Reliability Routing
Worked design
Practice
47. Design an Online Judge like LeetCode
Run strangers' code safely in single-use microVMs, return verdicts within 5 seconds, and rank 100,000 contestants live.
ClassicMedium
Caching Queues Databases
+8
Security AWS Firecracker Leaderboards Online judge Redis Sandboxing Amazon SQS
Worked design
Practice
86. Design an IP and URL Denylist
Deny requests by caller address, range or URL at a global edge, with lists from governments, threat feeds and detection reaching 300 proxies in seconds.
ClassicMedium
Security AWS Bloom filter
+3
CIDR Denylist Edge
Worked design
Practice
99. Design a Cross-Product Tagging System
One set of tags across Jira issues, Confluence pages and Bitbucket pull requests: batch renders, tag pages that never leak, suggestions, popular tags.
ClassicMedium
Databases Search Security
+6
AWS Collaboration DynamoDB Many to many OpenSearch Permissions
Worked design
Practice

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Classic designs 6

5. Design a Chat System

7. Design a File Storage Service

10. Design an API Gateway

47. Design an Online Judge like LeetCode

86. Design an IP and URL Denylist

99. Design a Cross-Product Tagging System