SystemDesign.io

55 Questions

Design a URL Shortening service like TinyURLEasy

Design PastebinEasy

Design InstagramEasy

Design Dropbox or Google DriveMedium

Design Facebook Messenger or WhatsAppMedium

Design Twitter for millions of usersEasy

Design Youtube or NetflixMedium

Design Typeahead Suggestion/AutocompleteHard

Design an API Rate LimiterHard

10.

Design a Distributed Metrics Logging and Aggregation SystemVery Hard

11.

Design a Distributed Stream Processing System like KafkaVery Hard

12.

Design a Key-Value StoreMedium

13.

Identify the K Most Shared Articles in Various Time Windows (24 hours, 1 hour, 5 minutes)Hard

14.

Design Web CrawlerMedium

15.

Design Facebook's News FeedMedium

16.

Design Yelp or Nearby FriendsVery Hard

17.

System to Collect Performance Metrics from Thousands of ServersHard

18.

Design Google CalendarMedium

19.

Design a Distributed Queue like RabbitMQHard

20.

Design Google Analytics - User Analytics Dashboard and PipelineHard

21.

Design a System for Sorting Large Data SetsEasy

22.

Top K Elements: App Store Rankings, Amazon Bestsellers, etc.Easy

23.

Design a Job SchedulerEasy

24.

Design a Notification Service at ScaleHard

25.

Surge Pricing System: Uber - Stream Processing, etc.Very Hard

26.

Netflix: Limit the Number of Screens Each User Can WatchHard

27.

Design an ETA Service and Location Sharing Between Driver and RiderVery Hard

28.

Design a Hotel Booking System: Room Availability, Reservation, BookingMedium

29.

Design an A/B Testing System (like Optimizely)Hard

30.

Design a Price Alert System for Amazon (or for Stock prices)Easy

31.

Design an IoC/Dependency Injection FrameworkVery Hard

32.

Design a Credit Card Processing SystemVery Hard

33.

Count Facebook Likes, Especially for High-Profile UsersMedium

34.

Design a Control Plane for a Distributed DatabaseVery Hard

35.

Design a User Login and Authentication System for a WebsiteMedium

36.

Develop a Weather ApplicationEasy

37.

Create a Document Management System like Wikipedia, Notion or Google DocsEasy

38.

Build a Marketplace Feature for FacebookEasy

39.

Design a System to Monitor the Health of a ClusterMedium

40.

Find a Rider for Uber or Uber EatsHard

41.

Design a Distributed Tracing SystemVery Hard

42.

Design Backend for an App to Distribute 6 Million Free Burgers in One HourMedium

43.

Design a File Downloader Library from Frontend to BackendHard

44.

Design a System to View Latest Stock Prices WorldwideEasy

45.

Develop a Photo Sharing Platform like Flickr or Google PhotosMedium

46.

Design an On-Call Escalation SystemMedium

47.

Design and Implement a Wire Transfer APIHard

48.

Design a Live Comments Feature for FacebookHard

49.

Design a Feature to Show the Number of Users Viewing a PageEasy

50.

Design Facebook Likes Feature with Live UpdatesEasy

51.

Create a System to Migrate Large Data to Google CloudVery Hard

52.

Design a Distributed BotnetHard

53.

Create a Distributed File Transfer System like BittorrentHard

54.

Design a Parts Compatibility Feature for an eCommerce SiteEasy

55.

Develop an Ads Management and Display System for a Social FeedVery Hard

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➡️

Count Facebook Likes, Especially for High-Profile Users

📕

📕 Here are some good solutions we found for this question:

Discussion on Blind: https://www.teamblind.com/post/System-Design-Question-How-does-FBInsta-storeretrieve-likes-NZEcwqVp

Detailed Solution: https://systemdesign.one/distributed-counter-system-design/

Video Solution: https://blog.interviewcamp.io/live-design-facebook-likes-distributed-counter

🙋

🙋 Here are some details you should know about this question:

To clarify: what scale are we looking at - what can the peak traffic be?

This is a distributed counters problem - how will you scale it as the likes grow?

How will you handle celebrity users, who get a huge number of counts really fast?

How do you deal with system failures? You will need some replication.

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