High-Level Design (HLD)
High-Level Design focuses on the overall architecture of a system—identifying core components, their interactions, data flow, and scalability strategies.
Available Designs
Rate Limiter
✓CompleteDesign a distributed rate limiting system to protect APIs from abuse and ensure fair usage.
Token BucketRedisDistributed
Last-Mile Delivery System
✓CompleteDesign a real-time delivery tracking platform like Zomato 10-min delivery with global scalability.
Real-time TrackingGeo-spatialEvent-driven
Planned Designs
URL Shortener
📋PlannedDesign a scalable URL shortening service like Bitly or TinyURL.
HashingRedirectionAnalytics
Notification System
📋PlannedDesign a multi-channel notification system supporting push, email, SMS, and in-app.
Priority QueuesTemplatesDelivery
Chat Application
📋PlannedDesign a real-time chat application like WhatsApp or Slack.
WebSocketsMessage OrderingPresence
Video Streaming Platform
📋PlannedDesign a video streaming service like YouTube or Netflix.
CDNTranscodingAdaptive Bitrate
HLD Interview Framework
What Interviewers Look For
| Aspect | What They Evaluate |
|---|---|
| Requirement Analysis | Can you ask the right questions? |
| System Decomposition | Can you break down complex problems? |
| Component Design | Do you understand core building blocks? |
| Scalability Thinking | Can you design for growth? |
| Tradeoff Analysis | Do you understand consequences of decisions? |
| Communication | Can you articulate your design clearly? |
Common Mistakes to Avoid
- Diving into details too early – Start with the big picture
- Ignoring requirements – Always clarify before designing
- Over-engineering – Start simple, scale as needed
- No capacity estimation – Back-of-envelope math matters
- Single points of failure – Consider redundancy and failover
- Ignoring operational aspects – Monitoring, alerting, deployment
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