System Design - performance
#01 Scalability

Build a QR Code Generation and Analytics Service Free

Design a system that generates dynamic QR codes at scale, tracks every scan with device and location metadata, and lets users update the destination URL without regenerating the QR code.

Read
#02 Data Engineering

Build a RAG Pipeline for an Enterprise Knowledge Base Premium

Design a Retrieval-Augmented Generation pipeline that ingests internal documents, chunks and embeds them, retrieves the most relevant context for each query, and re-ranks results before passing them to the LLM.

Read
#03 Data Engineering

Build a Real-Time Analytics Dashboard at 100B Events Premium

Design a product analytics system that ingests billions of events per day, supports sub-second aggregate queries over arbitrary time windows, and powers live dashboards without precomputing every possible metric.

Read
#04 Performance

Build a Real-Time Fraud Detection Engine Premium

Design a fraud detection system that evaluates every payment transaction in under 100ms using behavioral, velocity, and network signals, updates risk models continuously, and minimizes false positives that block legitimate users.

Read
#05 Data Engineering

Build Reddit's Post Ranking Algorithm Premium

Design a post ranking system that combines upvotes, downvotes, time decay, and engagement signals into a score that keeps feeds fresh without requiring full recomputation on every page load.

Read
#06 Distributed Systems

Build a Ride-Pooling Matching Engine Premium

Design a matching system that pairs multiple riders with overlapping routes into a single vehicle, calculates detour cost for each combination, and finds the optimal set of matches across thousands of concurrent requests within 2 seconds.

Read
#07 Microservices

Build a Self-Healing Service Mesh Premium

Design a service mesh that continuously monitors the health of every service instance, automatically reroutes traffic away from degraded nodes, and triggers remediation actions without human intervention.

Read
#08 Databases

Build a Semantic Search Engine with Hybrid Ranking Premium

Design a search engine that combines keyword-based BM25 scoring with dense vector similarity to handle queries where exact keyword matches are absent but semantic intent is clear.

Read
#09 Deployment

Build a Shadow Traffic / Dark Launch System Premium

Design a traffic mirroring system that duplicates live production requests to a canary service in real-time, compares responses for divergence, and generates a confidence report without any user-visible impact.

Read
#10 Distributed Systems

Build Slack's Channel Message Fan-Out and Unread Counts Premium

Design a messaging system that delivers channel messages to thousands of members in a large workspace, maintains accurate unread counts per user per channel, and syncs read state across multiple devices.

Read