System Design Track

Interview-style design questions with deep follow-ups

20 canonical system design problems. Each one starts from what you are building, walks through the engineering decisions, then closes with 10 to 15 follow-up scenarios you should be able to answer at the senior level.

20Problems

17Categories

3Levels

↗Source repo

🧭

Start here

System Design Roadmap — Beginner to Expert

A staged learning path covering every concept you need, in the order you need it. Foundations, storage, caching, messaging, scaling, distributed systems, and the interview craft.

7 stages60+ topicsNo prerequisites

→

📚

Reference library

System Design Concepts — Quick answers, in plain English

70 of the most common system design questions with short, scenario-driven explanations. Caching, queueing, consistency, load balancers, cloud trade-offs, and more.

70 topics12 sectionsIncluding AWS / GCP / Azure

→

20 of 20 problems

#1 Medium

Design a URL Shortener

Basics

encodingkv storecachingsharding +1

#2 Hard

Design a News Feed (Twitter / Instagram)

Social & Feeds

fan-outtimelinehot usersranking +1

#3 Hard

Design a Chat System (WhatsApp / Slack)

Real-Time Communication

websocketsmessage deliverypresenceordering +1

#4 Medium

Design a Rate Limiter

Reliability

token bucketsliding windowdistributed countersredis +1

#5 Medium

Design Typeahead / Autocomplete Search

Search

trieprefix treerankingcaching +1

#6 Hard

Design YouTube / Netflix (Video Streaming)

Streaming

cdnadaptive bitratetranscodingstorage tiers +1

#7 Hard

Design Uber / Lyft (Ride Sharing)

Geospatial

geohashh3matchingdispatch +1

#8 Hard

Design a Web Crawler (Googlebot)

Distributed Systems

bfsfrontierdeduplicationpoliteness +1

#9 Medium

Design a Distributed Cache (like Redis or Memcached)

Distributed Systems

consistent hashingreplicationevictionttl +1

#10 Medium

Design a Notification System

Messaging

fan-outretrydeduplicationmulti-channel +1

#11 Easy

Design an Approval Management Service

Workflow

state machinerole routingdelegationescalation +1

#12 Easy

Design a Shopping Cart Service

Session State

sessionpersistenceidempotencyinventory check +1

#13 Easy

Design a Todo List with Sharing and Collaboration

Collaboration

real-timewebsocketssharingpermissions +1

#14 Easy

Design a Coupon Code Redemption System

Concurrency

uniquenesssingle-useabuse preventionexpiration +1

#15 Easy

Design a Comment System (Threaded + Voted + Moderated)

User Content

nested datavotingmoderationsoft delete +1

#16 Easy

Design a Load Balancer

Networking

l4l7health checkssticky sessions +2

#17 Easy

Read-Heavy System Patterns

Patterns

cachingCDNread replicasmaterialized views +2

#18 Easy

Write-Heavy System Patterns

Patterns

batchingasyncpartitioningappend-only +3

#19 Easy

Design a Help Desk Ticketing System (like a basic Zendesk)

Workflow

state machineslaassignmentmulti-channel intake +1

#20 Easy

Design a File Upload & Share Service (Dropbox-lite)

Storage

chunked uploadshare linkspermissionsstorage tiers +1