A session replay service records a user’s browser interactions and reconstructs them for playback — enabling UX debugging, funnel analysis, […]

A matchmaking service pairs players into balanced, low-latency game sessions. The design touches skill rating systems, queue management, match formation

A thumbnail generation service converts uploaded images into resized, optimized variants for display at different sizes across web and mobile

A media upload service handles ingesting user files — images, video, audio, documents — reliably and at scale. The design

Overview An audit log service provides an authoritative, tamper-evident record of who did what to which resource and when. It

Problem Statement Design an investment portfolio tracker that stores positions, pulls real-time price feeds, calculates gain/loss, alerts on rebalancing drift,

Problem Statement Design the order book engine for a crypto exchange: handle limit and market orders, match them using price-time

Problem Statement Design a peer-to-peer payment service that lets users send money to one another, link external bank accounts, and

What Is a Delivery Tracking Service? A delivery tracking service monitors the lifecycle of a shipment from pickup through final

What Is a Ride-Share Matching System? A ride-share matching system pairs riders who need a trip with nearby available drivers.

What Is a Supply Chain Management Service? A supply chain management (SCM) service coordinates the flow of goods from suppliers

What Is a Promotional Code Engine? A promotional code engine generates discount codes, enforces usage rules, validates eligibility at checkout,

What Is a Gift Card Service? A gift card service handles the full lifecycle of stored-value cards: issuance, activation, balance

An expense management system handles the full lifecycle of employee expenses: from receipt capture in the field to reimbursement hitting

What Is a Code Execution Sandbox? A code execution sandbox is an isolated environment that compiles and runs arbitrary user-submitted