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.
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.
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.
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.
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.
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.
Build Spotify's Song Radio Feature Premium
Design a real-time playlist generator that uses a seed song to produce an infinite radio stream of acoustically and contextually similar tracks, personalizes the mix per listener, and avoids repetition across sessions.
Build Twitter's At-Mention Fan-Out for Celebrities Premium
Design a fan-out system that notifies the followers of a celebrity with 100 million followers when they are mentioned, without triggering a write storm that takes down the database.
Build Twitter's Trending Topics Pipeline Premium
Design a system that detects emerging viral signals from a stream of 500,000 tweets per second, computes trending topics per region, and refreshes trends every 60 seconds without reprocessing the full history.
Build Uber's Real-Time Driver-Rider Matching System Free
Design a matching system that pairs riders with the nearest available driver in dense urban areas within 2 seconds, handles thousands of concurrent match requests, and degrades gracefully during demand spikes.