I Found Codemia.io, Leetcode for System Design Interview, and It’s Awesome

A great place to practice System Design interview problems and Object Oriented Design problems

Hello guys, If you’re preparing for FAANG interviews, then you already know that Data Structures & Algorithms (DSA) and System Design are two key areas where you will be tested rigorously.

While LeetCode is the go-to platform for DSA, system design has always been a challenge — until now.

I recently found Codemia.io, and I must say, it feels like the LeetCode for System Design.

If you’ve struggled with structuring your system design answers, getting real feedback, or knowing whether your approach is correct, Codemia.io is a game-changer.

They not just have the biggest collection of System Design and OOP Design problem for practice they also have a free System deign course called Tackling System Design Interview Problems, which is a great free resource to learn essential System Design concepts.

It’s a short course with 2 hour of content but powerful and also have quizzes to test your skills. Here are all the key System deign topics you can learn on this free course:

Now, let’s checkout how Codemia.io can help you to prepare better for your System design and OOP Design interview and why I think its like LeetCode for System design.

Why System Design Needs a Platform Like Codemia.io?

Most system design resources today are long, text-heavy articles or expensive courses. The problem?

No hands-on practice — Reading about system design isn’t enough; you need to actively design solutions.
No structured progression — Unlike DSA, where problems are categorized by difficulty, system design prep often feels random and overwhelming.
No evaluation or expert feedback — You don’t just need an answer; you need to know why one design is better than another.

This is where Codemia.io changes the game.

What Makes Codemia.io Special?

Instead of just giving you theory-heavy content, Codemia.io provides an interactive, structured, and guided approach to system design. Here’s what I loved:

1. Real-World System Design Problems

Codemia.io has over 120+ system design problems, each with a structured approach similar to how LeetCode presents DSA problems.

For example, consider the classic “Design a URL Shortening Service” problem.

You start with:
✅ Functional and Non-Functional Requirements
✅ Capacity Estimation
✅ Database Schema and API Design
✅ High-Level & Low-Level Design

It guides you step by step so you don’t feel lost.

Bonus: You also get access to a drawing board where you can sketch your architecture, just like in a real system design interview.

And most importantly they also share expert solution for most of the problems to see how an expert should answer that question. For example, here is the solution of how to design a URL shortening service and its also available for free

2. Difficulty-Based Categorization

Just like LeetCode, both System design and object oriented design problems are categorized as:

Easy — Foundational concepts like Load Balancing, Caching, Message Queues
Medium — Scenarios like Rate Limiting, Search Autocomplete, Real-Time Chat Systems
Hard — Complex designs like Distributed Databases, Cloud Storage, and Microservices Architecture

Each problem also includes company tags so you can focus on what’s asked at FAANG and other top tech companies. For example, this how to design Twitter problem is a medium scale problem which you can see to get some experience. It’s also free.

3. AI-Powered Hints & Evaluations

One of the best features is AI-assisted guidance. You get to chat with the coach — the AI agent which will help you with the question and solution.

✅ If you get stuck, AI provides hints — just like LeetCode’s hint system.
✅ If you submit a design proposal, AI evaluates it against industry best practices.
✅ You get automated feedback on scalability, fault tolerance, and efficiency.

This bridges the gap between self-learning and expert mentorship.

Beyond System Design: Object-Oriented Design & AI Interviews

Codemia.io goes beyond just system design. It also covers Object-Oriented Design (OOD) Questions. If you don’t know , Object-Oriented Design is a common low-level design (LLD) round at FAANG.

Here are OOP problems you can solve on codemia.io to get some practice:

Classic problems like Parking Lot, ATM Machine, and Hotel Booking System
Step-by-step UML diagrams and class structure explanations
Comparison of different design patterns

If you struggle with OOD interviews, this is a goldmine.

Here is also all the OOP design problems available on Codemia.io

Codemia.io vs DesignGurus.io vs Educative

Now, let’s see how codemia.io compares with other popular resources we have used in past to prepare for System Design interview, notably DesignGurus.io whose Grokking the System Design Interview course is also one of my favorite and Educative.io, whose modern System design course is also a great resource.

You can see that codemia.io have highest number of practice problems, 120+ and growing, no other platform have that many questions which is also the big plus point of this platform and that’s why I called it “Leetcode of System Design”.

Second important point is expert written solution, also known as editorial solution in this website. There are mor than 80+ such solution which are great resource to compare your solution, learn from them and also find how to answer such questions.

What point to mention, what should you discuss, tradeoffs and so much more.

Another plus point of codemia.io is that it has object oriented programming questions which is not available in other courses, though DesignGurus.io have Grokking the Object Oriented Design Interview course which you can use for OOP design practice, but again when it comes to numbers, codemia.io wins.

So far we have compared the content but if we talk about platform, codemia.io have especially designed for online practice, particulary deisgn questions.

It comes with Interactive learning tools, interactive feedback and evaluation, chatbot and a great design tool for drawing. No other platform support so much feature which is essential to master system design.

Then there is community and you can also see the solution of other folks to learn from them. I love this feature as it allows me to see what other folks are thinking and how they solve that problem. This comparative analysis have helped me a lot to learn key system design concepts.

Overall, I think, codemia.io is a great platform to prepare for System design and OOP design interview. You may find courses but its hard to find a platform like this.

I highly recommend it for anyone preparing for System Design and Tech interviews. And, if you want to join now, you can also use discount code PROMOTION20 to get 20% off now.

Here is the link — 20% OFf on Codemia.io

Final words

If you’re preparing for FAANG system design interviews, Codemia.io is a must-try. It solves the biggest problems in system design prep:

✅ Structured learning path (instead of random articles)
✅ Real-world hands-on practice (instead of just reading)
✅ Expert evaluation & AI feedback (so you know what to improve)
✅ Mock interviews to simulate real conditions

I’m still exploring Codemia.io, but what I’ve seen so far is truly impressive.

If you’ve tried it, let me know what you liked or didn’t like.

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

I Found Codemia.io, Leetcode for System Design Interview, and It’s Awesome 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