Careem Android Interview Series

(Part 2): System Design Challenge

Intro Hook

This is Part 2 of my Careem Android interview journey. If you missed Part 1 (SOLID Principles & Architecture), read it here.

After a fundamentals-heavy first round, Round 2 was about applying those principles in a real-world system design challenge.

The Problem

“Design an Android system to display product lists with basic details, keep them updated in real-time as price/availability changes, and allow navigation to product details.”

Oh, and it needs to handle thousands of products — so pagination was a must.

My Approach

1. Architecture → MVVM + Repository Pattern.
2. Pagination → Paging 3 for seamless infinite scrolling.
3. Real-Time Updates → WebSockets for instant changes; fallback to push notifications.
4. Navigation → Jetpack Navigation for smooth detail transitions.
5. State Management → ViewModel to preserve list state on orientation changes.
6. Offline Handling → Room DB cache with background sync.

Why This Works

• MVVM + Repository → Clean separation, easy testability.
• Paging 3 → Efficiently handles large datasets.
• WebSockets → True real-time without constant polling.
• Offline-first → Keeps the app usable even without internet.

Takeaways

• Careem wants devs who think about scalability from the start.
• Real-time isn’t just a backend thing — mobile architecture has to support it.
• Strong fundamentals from Round 1 fed directly into my Round 2 design choices.

⬅ Missed Part 1? Read Careem Android Interview — SOLID Principles & Architecture

Tags: Android Interview Careem System Design MVVM Mobile Architecture Kotlin WebSockets