Build Amazon's Product Search Ranking Premium
Design a search ranking system that incorporates real-time inventory, pricing, and sales velocity signals into results, personalizes rankings per user, and re-indexes a product catalog of 500 million items.
Build Amazon's Review Aggregation Pipeline Premium
Design a review processing pipeline that deduplicates submissions, filters fraudulent reviews using behavioral signals, computes rolling star averages, and surfaces the most helpful reviews per product.
Build a Change Data Capture Pipeline Premium
Design a CDC pipeline that streams every database write to downstream consumers in the order they occurred, preserves transactional boundaries, and guarantees no event is dropped even if a consumer is temporarily offline.
Build a Columnar Storage Engine with SSTable and Compaction Premium
Design a write-optimized storage engine that buffers writes in memory, flushes them to immutable SSTables on disk, and runs background compaction to merge files while keeping read amplification low.
Build a Comment Threading System with Infinite Nesting Premium
Design a comment system that supports infinitely nested replies, renders full comment trees efficiently at any depth, and allows collapsing subtrees without loading the entire thread.
Build a Content Moderation Pipeline Premium
Design a content moderation system that uses ML classifiers to automatically detect policy violations in text, images, and video, routes borderline cases to human reviewers, and minimizes both over-removal and under-removal.
Build a Follow Recommendation Engine Using Graph Traversal Premium
Design a 'Who to Follow' recommendation engine that traverses a social graph of 500 million nodes to find second-degree connections, scores candidates by mutual friend count and activity, and refreshes recommendations daily.
Build a Game Replay Storage and Scrubbing System Premium
Design a replay system that records every game event, lets players scrub to any point in a replay with under 1 second seek time, and serves millions of replay requests per day without straining the game servers.
Build Gmail's Spam Detection Pipeline Premium
Design a spam classification system that processes 300 billion emails per day, classifies each one in under 100ms before delivery, and continuously retrains models as spammers adapt their tactics.
Build Google Photos Duplicate Detection Pipeline Premium
Design a pipeline that detects near-duplicate photos across 28 billion uploads per day using perceptual similarity rather than byte-level matching, and does so without storing a full copy of every image.