Practice series
Streams, metrics & aggregation
Clicks, counters, dashboards, alerts, windows, and late-event correctness.
- 01Free
Ad Click Aggregator
Design an ad click aggregation system that ingests millions of click events per second and serves near-real-time plus historical aggregate metrics to advertiser...
Meta - 02Preview
Metric Monitoring and Alerting
Design the metrics pipeline behind a monitoring platform — the path from an SDK on thousands of hosts emitting numeric measurements, through streaming pre-aggre...
Uber - 03Preview
Monitoring and Alerting
Design the alerting and observability layer of a monitoring platform — the system that evaluates rules against incoming signals, decides who gets paged, and kee...
Practice bank - 04Free
Top K Songs (Spotify)
Design Spotify's Top-K most-played songs feature — compute top charts over sliding time windows at listening-event scale.
Spotify / Meta - 05Preview
Fraud Detection
Design a real-time ML fraud/risk scoring system that scores payment transactions in under 100 ms.
Stripe