Top 10 System Design Interview Questions in 2025 (and How to Approach Them)

Don’t let system design interviews intimidate you. Learn about 2025’s 10 must-know system design questions — from URL shorteners to ride-sharing — and how to solve each one.

This blog highlights the top 10 questions of 2025 – from URL shorteners to ride-sharing – and offers tips on how to approach each confidently.

Facing a system design interview soon?

It’s normal to feel anxious because these questions are open-ended.

The good news is you can handle them by breaking the problem into parts.

In this post, we walk through ten common system design scenarios (from easy to hard).

For each, we outline the problem and key considerations in the solution.

Let’s get in!

1. Design a URL Shortener – Difficulty: Easy

• Unique ID Generation: Generate a short code by converting a numeric ID into Base62 (using characters 0-9, a-z, A-Z).

• Storage & Scaling: Map short codes to original URLs in a database (with caching for hot links). Use load balancers and shard/replicate the database to handle a huge number of links.

2. Design Pastebin (Text Storage) – Difficulty: Easy

• Storage & Key: Store the text in a database or blob storage and create a unique key (e.g. a random string) for each paste. Optionally allow pastes to expire after some time.

• Access & Performance: Provide an API or web interface to create and retrieve pastes. Enforce size limits per paste, and use caching or multiple servers with load balancing to handle high traffic.

3. Design an API Rate Limiter – Difficulty: Medium

• Limit Algorithm: Use a token bucket (or similar) to allow a fixed number of requests per interval (e.g. 100 requests per minute, with tokens refilling over time).

• Distributed Enforcement: Keep counters in a fast in-memory store (like Redis) so all servers share usage data. If a client exceeds the limit, return an HTTP 429 (Too Many Requests) error.

4. Design a Social Media Feed – Difficulty: Medium

• Feed Updates: Choose fan-out on write (push new posts to all followers’ feed storage) vs fan-out on read (fetch posts on-demand when a user opens the app). Pushing on write = faster reads; on read = easier to support users with millions of followers.

• Caching & Refresh: Cache feeds for quick reads. Update feeds asynchronously or via real-time notifications when new posts arrive.

5. Design a Chat Service – Difficulty: Medium

• Real-Time & Scale: Use WebSockets (persistent connections) so messages deliver instantly. Run many chat servers behind a load balancer. Ensure each user’s messages go through a consistent server or are synchronized across servers to preserve order.

• Message Storage: Save chat history in a database or queue so messages aren’t lost. If a user is offline, hold their messages and deliver when they reconnect.

6. Design an Online Shopping System – Difficulty: Medium

• Service Separation: Split the system into microservices for key functions. For example: a Product Service for item info and inventory, an Order Service for cart & order processing, and a Payment Service for transactions. This makes it easier to scale and maintain each part.

• Search & Inventory: Use a search engine (e.g. Elasticsearch) for product search and a database for the catalog. Ensure inventory is updated atomically when orders are placed (to maintain consistency). Cache popular items and use a CDN for static content (images, etc.) to speed up page loads.

7. Design a File Storage Service – Difficulty: Hard

• File Storage: Break files into chunks (e.g. 4 MB each) and store them in a distributed system or cloud storage. Replicate each chunk to multiple servers for reliability.

• Metadata & Sync: Keep a metadata database to track file info (which chunks, locations, versions, permissions, etc.). Send notifications to client apps when a file changes so they can download updates. Handle conflicts from simultaneous edits by versioning or locking files.

8. Design a Web Crawler – Difficulty: Hard

• Crawl Queue: Maintain a queue of URLs to crawl, with priority and politeness (don’t overload any single site). Multiple crawler machines pull from this queue and fetch pages in parallel.

• Parsing & Indexing: When a page is fetched, parse it to extract text and new links. Add unseen links to the queue. Send page content to an indexer service to update a search index (so users can later query information). Track visited URLs to avoid duplicates.

9. Design a Video Streaming Platform – Difficulty: Hard

• Video Processing: Upon upload, encode the video into multiple resolutions/bitrates (e.g. 480p, 1080p) and store those versions. Videos are chopped into small segments for adaptive streaming (the client can switch quality based on bandwidth).

• Global Delivery: Use a Content Delivery Network (CDN) to cache video segments on servers around the world. Users stream from the nearest CDN node to reduce lag. Design the system to auto-scale for spikes in viewership and use load balancers to spread traffic.

10. Design a Ride-Sharing Service – Difficulty: Very Hard

• Real-Time Matching: Continuously collect GPS locations from drivers. When a rider requests a ride, a dispatch service finds a nearby driver (using geospatial queries). Notify the driver and rider, and provide real-time updates as the driver approaches.

• Scaling & Services: Break the system into services (dispatch, maps/ETA, pricing, payments, etc.). Each service can scale horizontally to handle heavy load. Build in fault tolerance so a partial outage doesn’t take down the entire system.

Conclusion

System design interviews can be overwhelming, but breaking problems into components makes them manageable.

In an interview, start by clarifying requirements and assumptions.

As you sketch your solution, explain the pros and cons of your choices to show you can weigh trade-offs.

Prepare for system design interviews with Grokking the System Design Interview course by DesignGurus.io.

For more practice, check out Grokking System Design Fundamentals and Grokking the Advanced System Design Interview. These resources cover many of the scenarios above in depth and can help you sharpen your system design skills.

Good luck with your interview prep, and happy designing!