BeginnerAvailable
URL Shortener
Create short links, redirect users fast, and track basic click analytics.
- FAANG
- Backend
- SaaS
System Design Interview Preparation
Learn how to design real-world systems step by step for backend and Java interviews.
Top 20 System Design Questions
Showing 20 of 20 questions
BeginnerAvailable
Rate Limiter
Protect APIs by limiting how many requests a client can send in a time window.
- FAANG
- Backend
- Java
Mid-levelAvailable
Distributed Cache
Speed up reads with a shared cache across many application servers.
- FAANG
- Backend
- Java
Mid-levelAvailable
News Feed
Show a personalized feed of posts with ranking, fan-out, and pagination.
- FAANG
- Backend
Mid-levelAvailable
Chat / Messaging System
Design one-to-one and group chat with online status and message delivery.
- FAANG
- Backend
BeginnerAvailable
Notification System
Send email, SMS, and push notifications without slowing down core APIs.
- SaaS
- Backend
- Java
Mid-levelAvailable
File Storage like Dropbox
Upload, sync, and share files with metadata, versions, and chunked storage.
- Backend
- SaaS
- FAANG
SeniorAvailable
Video Streaming like YouTube / Netflix
Ingest videos, transcode them, and stream smoothly to millions of viewers.
- Backend
- FAANG
- SaaS
Mid-levelAvailable
Search Autocomplete
Suggest search terms in a few milliseconds as the user types.
- Backend
- FAANG
- SaaS
SeniorAvailable
Ride Booking like Uber
Match riders and drivers in real time with location, pricing, and trip state.
- Backend
- FAANG
- Fintech
Mid-levelAvailable
Food Delivery / Order Workflow
Track an order from restaurant to rider to customer with status updates.
- Backend
- SaaS
- Fintech
SeniorAvailable
Payment System
Move money safely with idempotency, ledgers, and failure handling.
- Backend
- Fintech
- SaaS
Mid-levelAvailable
E-commerce Cart, Order, and Inventory
Keep cart, stock, and checkout consistent when many shoppers buy at once.
- Backend
- SaaS
- Java
SeniorAvailable
Ticket Booking System
Hold seats for a short time and prevent double booking under high traffic.
- Backend
- FAANG
- Fintech
SeniorAvailable
Logging, Metrics, and Observability Platform
Collect logs, metrics, and traces so teams can debug production issues.
- Backend
- SaaS
- Java
Mid-levelAvailable
Web Crawler
Discover pages, fetch them politely, and store content for search or analysis.
- Backend
- FAANG
SeniorAvailable
Distributed Queue
Buffer work between services so producers and consumers can scale independently.
- Backend
- FAANG
- Java
Mid-levelAvailable
API Gateway
Put a single entry point in front of services for routing, auth, and limits.
- Backend
- SaaS
- Java
Mid-levelAvailable
Authentication and Session System
Sign users in, keep sessions safe, and handle tokens across many services.
- Backend
- SaaS
- Java
SeniorAvailable
Collaborative Document Editor
Let many people edit the same document at the same time without losing data.
- Backend
- FAANG
- SaaS
Related case studies
Longer architecture write-ups already published on JavaThoughts.