Design a Geospatial Weather Observation Service
Design a service that receives observations from a large fleet of geolocated weather sensors, including airborne sensors. Users should be able to request current conditions for a location, view a regional weather heatmap, and query daily minimum and maximum values for a historical region. Explain the ingestion path, data model, APIs, aggregation strategy, caching, and failure behavior.
Design a Package Locker Service
Design a package-locker service. During checkout, customers can discover eligible lockers near a delivery location. The system allocates a suitable compartment, supports courier drop-off, issues a secure pickup credential, confirms collection, and releases or reassigns capacity after expiry or failure. Explain the APIs, state model, allocation strategy, consistency boundaries, security, and operational behavior at scale.
Design a Review and Rating System
Design the review and rating system for a large marketplace. Verified customers can rate a purchased product, optionally write a review, and later edit or delete it. Product pages must show the aggregate score, rating distribution, and review lists under several sort orders. Moderation may hide or remove content, and every state change must update customer-visible aggregates correctly. Define the APIs, data model, read and write paths, consistency boundaries, scaling strategy, and failure recovery.
Design Food Delivery System
Design a food-delivery marketplace for customers, restaurants, and couriers. Customers should be able to discover nearby restaurants, place an order, and follow its progress until delivery. Restaurants need to accept and prepare orders, while couriers need suitable work assigned as conditions change in real time. The platform operates across many cities and must remain usable when traffic spikes or one participant becomes temporarily unreachable. Clarify the initial scope, then walk through your design.
Design Netflix
Design a system like Netflix that allows users to browse, stream, and interact with video content. Focus on the core platform including video delivery and user interactions.
Design Twitter
Design a system like Twitter, a social media platform that allows users to post short messages, follow other users, and view a timeline of posts from users they follow.
Design Uber
Design a ride-sharing service like Uber that connects riders with nearby drivers and facilitates the entire ride experience from requesting to completion.
Large-scale ticketing system design
Design a large-scale ticketing system capable of handling millions of users during peak events. Support event discovery, seat selection, temporary holds, purchase, payment, promo codes, mobile ticket validation, and administrative reporting while preventing overselling.
Typeahead Suggestion / Autocomplete Design
Design a typeahead (autocomplete) service that returns the top-3 suggestions for the prefix the user is typing. Suggestions should be ordered by a combination of popularity (frequency) and recency. The system must provide real-time responses with very low latency, scale to large traffic, and be highly available.