System Design Interview Questions
Practice the exact questions companies are asking right now.
Design a payment processing system
Scenario Design a backend payment system for an online product that supports: - One-time charges and refunds. - Idempotent payment APIs (clients may r...
Design first-time Kubernetes deployment in new cloud
Scenario You need to stand up a new compute cluster on a new cloud account/subscription (greenfield). The team wants a simplified, practical plan for ...
Design a CI/CD system with stuck-job handling
Scenario Design a CI/CD platform similar to GitHub Actions/Jenkins that: - Triggers pipelines on events (e.g., push/PR/merge). - Runs pipelines as a D...
Design a CI/CD system with live log streaming
System Design Prompt: CI/CD Platform (shell-script jobs) Design a CI/CD system that can: 1. Allow users to define pipelines consisting of multiple job...
Design a donations service with 3-day rolling totals
Design a service that ingests donations and serves rolling 3-day donation totals. Requirements Core features 1. Ingest donation events: - Each dona...
Design a hotel search and booking system
Assume you are asked to design a hotel search and booking service that runs inside a larger platform (similar to an online travel agency). Requirement...
Optimize HTTP requests for speed and limits
You are building a service that needs to send HTTP requests to a large number of URLs (for example, a simple web crawler or data fetcher). The naive i...
Design a crash-resilient file system
Prompt Design a resilient file system that can recover file contents correctly after a system crash (e.g., power loss / kernel panic). The interviewer...
Design a digital game shop backend
Design the backend for a simple digital game shop where users can buy virtual items (e.g., games, in‑game currency, skins) using credits in their acco...
Design a news aggregator system
System Design: News Aggregator Design a news aggregator (similar to a “Top stories”/Google News style product) that ingests articles from many publish...
Design a search query autocomplete system
Question Design a search autocomplete system that suggests completions as the user types. Requirements - Sub-100ms latency per keystroke. - Suggestion...
Validate order book data across multiple databases
Assume your organization stores order book–related data in multiple databases (e.g., one for raw exchange messages, one for normalized orders, one for...
Design a compliant multi-tenant analytics platform
Prompt Design a multi-tenant data analysis platform for government and enterprise customers. The interviewer emphasizes that the key challenge is not ...
Design an in-memory order matching engine
You are asked to design an in-memory order book / order matching system for a single electronic trading venue. The implementation language is C++, and...
Design large-scale near-duplicate video detection
Design a product-grade fuzzy (near-)duplicate detection system for a large short-video platform. You need to detect whether an uploaded video is a nea...
Design reliable high-volume chatbot system
You are designing the backend for a chatbot / AI assistant service (similar to a support bot or meeting assistant). Many users may send messages at th...
Evaluate impact of short videos in feed
Scenario You work on a social app’s main News Feed. The team wants to introduce a short-form video module ("Reels") into the feed. Prompt 1. How would...
Design GPU credit allocator
System Design: GPU Credits Allocation and Fair Usage Context You are designing a multi-tenant platform that provides access to GPU compute across many...
Design exchange–trading system message flow
Design the message contract and flow between a firm's trading system (OMS/EMS) and an external exchange. Assume: - The trading system sends orders and...
Design a metrics platform without alerting
Design a metrics platform (like a simplified Prometheus/Datadog metrics product) that supports collecting, storing, querying, and visualizing metrics....