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Elevator System Design
A structured walkthrough of Elevator System Design, covering clarifying questions, request modeling, scheduling trade-offs, request assignment logic, real-world traffic scenarios (rush hour and mixed flow), failure/safety handling, scaling from centralized to zoned control, and the metrics used to tune performance in production.
Khayyam Hashmi
Jan 30 · 2026
ATM System Design
In this blog, we’ll build an ATM System Design, explaining how transactions stay ACID-correct, introducing a withdrawal state machine (with reversal and reconciliation), covering interbank routing and settlement, and showing how to think about fraud prevention and observability.
Zarish Khalid
Jan 29 · 2026
CamelCamelCamel System Design Explained
CamelCamelCamel System Design explained, covering price tracking pipelines, historical data storage, alert evaluation, scalability, and real-world trade-offs.
Mishayl Hanan
Jan 29 · 2026
Ad Click Aggregator System Design
A practical, interview-focused blog to designing an ad click aggregator that powers real-time dashboards and accurate billing using a streaming + batch architecture, with deduplication, late-event handling, skew mitigation, and auditability.
Khayyam Hashmi
Jan 28 · 2026
Mobile System Design Explained
Mobile System Design explained, covering client-server architecture, offline support, data sync, API design, scalability, and real-world mobile constraints.
Mishayl Hanan
Jan 28 · 2026
Deliveroo System Design Explained
Deliveroo System Design explained, covering order flow, rider dispatch, real-time tracking, scalability, and fault-tolerant food delivery systems.
Mishayl Hanan
Jan 27 · 2026
Live Comments System Design
A live comments system design blog focusing on system for streams with 100k+ viewers. It covers at-least-once delivery with client dedupe, per-stream ordering via server sequence numbers, durable log + replay, cold start/catch-up with last_seen_seq, moderation as a higher-priority control plane, and hot-stream degradation strategies with concrete metrics.
Zarish Khalid
Jan 26 · 2026
Instacart System Design Explained
Instacart System Design explained, covering real-time grocery ordering, shopper dispatch, substitutions, order state management, and scalable delivery systems.
Mishayl Hanan
Jan 26 · 2026
Chat System Design
An interview-focused blog to designing a scalable chat system: durable message storage with per-conversation ordering, at-least-once delivery with deduplication, multi-device sync via per-device cursors, group chat fan-out trade-offs, and the correct role of push notifications (wake-up hint, not delivery). It also covers presence/typing as eventually consistent and the metrics you’d use to operate the system.
Khayyam Hashmi
Jan 22 · 2026
