System Design - scalability
#01 Data Engineering

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.

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#02 Distributed Systems

Build Google Docs Real-Time Collaborative Editing Premium

Design a collaborative document editor where multiple users can type simultaneously, see each other's cursors in real-time, and never lose edits even when two users modify the same paragraph at the same time.

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#03 Distributed Systems

Build Google Drive's File Sync Engine Premium

Design a file synchronization system that detects changes on any device, propagates them to all other devices within seconds, handles concurrent edits, and resolves conflicts without data loss.

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#04 Distributed Systems

Build Google Maps ETA Prediction Under Live Traffic Free

Design a route ETA system that incorporates real-time traffic signals from millions of moving devices, recalculates ETAs en route as conditions change, and serves predictions with under 200ms latency.

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#05 Data Engineering

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.

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#06 Scalability

Build Google Search Autocomplete Premium

Design a typeahead suggestion engine that returns the top 10 relevant completions for any search prefix in under 50ms, personalizes results per user, and updates suggestions based on trending queries in near real-time.

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#07 Data Engineering

Build a Social Media Hashtag Trending System by Region Premium

Design a system that indexes every post's hashtags, computes trending tags per geographic region updated every minute, and surfaces breakout trends that are gaining velocity even before reaching high absolute volume.

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#08 Scalability

Build Instagram Explore Real-Time Recommendation Engine Premium

Design a content discovery system that generates a personalized Explore grid for 2 billion users, refreshes recommendations as users scroll, and surfaces trending content within minutes of it going viral.

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#09 Data Engineering

Build Instagram Stories Expiry and Archival Pipeline Free

Design a system that automatically expires 500 million Stories after 24 hours, moves them to cold archival storage, and lets users retrieve archived Stories on demand without impacting live traffic.

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#10 Databases

Build an Inverted Index for Full-Text Search at 10B Documents Premium

Design a full-text search engine that builds and maintains an inverted index over 10 billion documents, returns results with relevance ranking in under 100ms, and updates the index in near real-time as documents are added.

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