Top 20 System Design Problems You Cannot Miss in 2025

Frequently asked System Design Problems with solutions and explanations and resources.

Hello guys, if you’re preparing for system design interviews in 2025, one thing is clear: brushing up on basic concepts won’t cut it anymore.

Today’s interviews are far more practical, and interviewers expect you to design real-world systems that are scalable, fault-tolerant, and performant.

Whether you’re aiming for top tech companies like Google, Meta, Amazon — or up-and-coming AI startups — mastering system design is non-negotiable, even for senior developers.

The good news? You don’t need to hunt around for scattered resources like articles, blogs, YouTube channels or Udemy courses.

One platform that stands out for system design prep in 2025 is Codemia.io, Leetcode for System Design.

Codemia.io gives you:

  1. Real-world system design questions
  2. Clear explanations with free solutions for many problems
  3. A diagramming editor to practice like real interviews
  4. An ever-growing library curated by senior engineers
  5. Editorial solutions created by experts
  6. AI assisted learning and problem solving
  7. Expert evaluation

All this makes Codemia.io a go-to resource for System Design interview prep and I have been using it for my interview preparation now.

Earlier, I have talked about Is Codemia.io Good Place to Prepare for System Design? and in this post, I’ll share 20 must-solve system design problems, including free questions and solutions from Codemia.io that you should absolutely practice before your next interview.

They have both free and paid questions and I am going to share them both for you.

Top Free System Design Problems with Solutions

These are completely free to access, and they include detailed editorials, diagrams, and architecture breakdowns on Codemia.

1. Design a URL Shortening Service (Like TinyURL)

In this problem you will learn to implement hash-based URL shortening, handle collisions, and manage redirection at scale.

Here are both Functional and non-functional requirement

Functional:

1. Given a long URL, create an associated short URL.

2. Given a short URL, return the associated long URL.

Non-Functional:

  1. Availability — This service has to be highly available. Especially functionality (2) (redirection).
  2. Response time — Functionality (2) has to have low response time, e.g., less than 10ms. Functionality (1) (creating short URL) can takes more time — less than 10 seconds.
  3. Scalability — We will get more and more requests to create short URLs, so the storage has to be highly scalable.

By the way, you should keep the requirements scope small. You only have 35–50 min in an interview. If you have a lot of requirements, you’d risk running out of time.

We could add other requirements like custom link. But we will start with a small set of requirements. Easier to expand later than shrink.]

You an further see the 📘 Solution once you have tried it yourself.

2. Design Twitter

In this problem you will design a messaging app like X with Follow/unfollow logic, timeline generation, tweet distribution, and fanout strategies explained.

Here are detailed functional and non-functional requirements for you:

Functional:

  1. User can tweet (send) up to 140 character message.
  2. User can follow other users.
  3. User can like other users’ tweets.
  4. User’s home feed will show tweets from the users they are following.

The home feed will show top K popular tweets, based on the number of likes they receive, and the number of the followers the author has.

Non-Functional:

  1. Scalability. It will have to serve a very large population, e.g., 500M DAU.
  2. Response time. User has to see tweets quickly. When user opens home feed, the first 10 tweets should show up within 500ms.
  3. Availability.

See the 📘 Solution once you have tried your hand.

3. Design Ticketmaster

This is a great System design problem to learn Concurrency handling, seat locking, and avoiding double bookings.

Here are the detailed functional and non-functional requirements:

Functional:

User is able to:

  1. Search for a theater by city or ZIP code.
  2. After selecting a theater, search for movies shown the the theater.
  3. After selecting a movie, select which show (e.g. show starting at 1PM, 3PM, 5PM, …)
  4. After selecting a show, user is presented a list of available seats.
  5. User can select the seats and finalize the booking.

Non-Functional:

We focus on the following aspects, as they are the most important:

  1. Consistency — once a booking is made, it has to be respected. No double bookings.
  2. Concurrency — multiple users are interacting with the service to view seats and book seats. Make sure system handles concurrent accesses and provide consistent bookings.
  3. Scalability
  4. Fault Tolerance

You can also refer the 📘 Solution once you have tried your hand.

4. Design a Parking Lot System

This is another free System Design problem on Codemia.io where you would design using Object-Oriented Design and handle both functional and non-functional requirement like

Functional:

  1. User can reserve a parking spot.
  2. User pays for the reservation.
  3. User can park a car on the parking spot.
  4. User can leave before the reservation time expires.
  5. One common error case to handle is when a user makes a reservation, but fails to show up. In this case, we would charge for the first 24 hours..

Non-Functional:

  1. Scalability. We are designing this for an international company who has 1000s of parking lots across nations.
  2. Availability.
  3. Consistency. Once a reservation is made, the parking spot must be available for the user. No double-booking.

Once you have tried it yourlsef you can also see the 📘 Solution here

Top Premium System Design Problems Worth Unlocking

While these are paid on Codemia, they are worth every penny if you’re serious about mastering advanced system design.

5. Design Facebook Messenger

Real-time chat, message delivery, synchronization across devices, and storage optimization.

6. Design a Resource Allocation Service

Perfect for scheduling systems like Uber, Lyft, or shared resource booking tools.

7. Design a Fitness Tracking App

Track steps, integrate GPS, sync across devices.

8. Design a Weather Reporting System

Ingest and distribute real-time sensor data, cache weather forecasts, and scale APIs.

9. Design Pastebin

Expiration logic, storing snippets, short link redirection.

10. Design a Nested Comments System

Focus on tree structures, pagination, and moderation workflows.

11. Design Online Presence Indicator

Track real-time status updates, efficient updates via websockets, and availability caching.

12. Design a Vending Machine System

Inventory management, embedded system integration, payment gateway design.

13. Design a Tagging Service

Tag hierarchy, search performance, and recommendation systems.

14. Design Craigslist

Categorized listings, search index, and ad posting flows.

15. Design Multi-Device Screenshot Capture System

Manage screenshots from remote devices, sync, and store them securely.

16. Design a Network Path Analyzer

Track, simulate, and monitor multi-hop network paths.

17. Design an Employee Swap System

Like a job board within your org — matching roles with available employees.

18. Design a Conference Room Booking System

Calendar integration, booking slots, room conflicts, and availability display.

19. Design a Video View Count System

Optimize counting at high scale, prevent fraudulent views, aggregate with accuracy.

20. Design an API Rate Limiter

Implement sliding window or token bucket algorithm at scale for rate-limiting APIs.

21. Design a Resource Management System (OOD)✨ Bonus

Object-Oriented Design problem to prepare for FAANG and tier-1 companies. Includes class diagram practice.

Why Codemia.io Is My Go-To System Design Interview Prep Platform in 2025

I have read books, tried many courses and while all of them provide value the most value I have got from practicing the problem my myself and using AI for assistant.

Also most platforms just give you a PDF solution or a video. But Codemia.io gives you:

  1. Real-world, open-ended problems
  2. Rich editorials with diagrams and best practices
  3. A built-in diagramming tool to practice visually
  4. Discussion board, solution submissions, and design patterns
  5. AI Assistance on both problem solving and evolution.

Whether you’re a beginner or preparing for Staff Engineer interviews, Codemia.io has questions from simple CRUD systems to large-scale distributed architectures.

They also have this nice System Design roadmap where you can click the topic and practice the related System Design problems

For example, when you click Artificial Intelligence you can see these problems to practice

💡 Pro Tip: Start with the free problems + editorials. Once you’re comfortable, invest in the premium ones to tackle the more complex scenarios.

Conclusion

That’s all about Top 20 System Design Problem you can practice to hone your software design skills in 2025. These questions also touch based different topics like handling load, handling concurrency etc.

System Design isn’t just an interview topic anymore — it’s a must-have skill for modern software engineers. In 2025, your ability to design scalable systems can determine whether you land that Staff Engineer, SDE III, or Senior Software Engineer role.

With Codemia.io, you get a structured way to learn, free questions to practice, and a real-world environment to simulate interviews.

So, bookmark this list, tackle one problem a week, and you’ll be amazed at how fast your system design confidence grows.

Ready to get started? Check out Codemia.io System Design Library and pick your first problem today!

Other System Design Articles and Resources you may like

Thanks for reading this article so far. If you like this article then please share with your friends and colleagues. If you have any questions feel free to ask in comments.

P. S. — They are also offering 20% discount now and you can get access for just $59 for one year, original price is $120 so you have a chance to save$60 and also learn System design better.

Master System Design Interviews Through Active Practice

Top 20 System Design Problems You Cannot Miss in 2025 was originally published in Javarevisited on Medium, where people are continuing the conversation by highlighting and responding to this story.

This post first appeared on Read More

Related Posts