Design a Payment System
5 min read Design a payment system like Stripe, PayPal, or an internal payments platform at a company like Uber or Amazon. This […] Read article
System Design
System Design
Design a News Feed (Facebook-style)
4 min read Design a news feed system like Facebook’s. This is a richer problem than the Twitter feed design — Facebook’s feed Read article
System Design
Design a Distributed Key-Value Store
5 min read Design a distributed key-value store like DynamoDB, Cassandra (its KV layer), or Redis Cluster. This is one of the most Read article
AI/ML Interview Questions
Classification Metrics: Precision, Recall, F1, and AUC-ROC
6 min read Classification metrics are one of the most frequently misused concepts in ML interviews. The wrong answer: “I use accuracy.” The Read article
System Design
Design Dropbox / Google Drive
5 min read Design a file storage and sync service like Dropbox or Google Drive. This problem tests your ability to handle large Read article
System Design
Design a Web Crawler
5 min read Design a web crawler that can index a significant portion of the internet. This question tests whether you understand distributed Read article
AI/ML Interview Questions
How Backpropagation Works: The Chain Rule in Neural Networks
6 min read Backpropagation is the algorithm that makes training deep neural networks possible. Every interviewer for ML engineering or research roles expects Read article
System Design
System Design: Ride-Sharing App (Uber / Lyft)
6 min read Designing a ride-sharing app is a rich system design problem that tests your ability to handle real-time location data, geospatial Read article
System Design
System Design: Notification System (Push, Email, SMS)
6 min read A notification system is asked at almost every senior system design interview because it surfaces real architectural challenges: fanout at Read article
System Design
System Design: Search Autocomplete (Google Typeahead)
6 min read Search autocomplete — the suggestions that appear as you type into Google, Amazon, or YouTube — is a deceptively interesting Read article
AI/ML Interview Questions
Overfitting and Regularization: L1, L2, Dropout, and Early Stopping
6 min read Overfitting is the most common failure mode in machine learning. Every ML interview will test your ability to recognize it Read article
System Design
System Design: YouTube / Video Streaming Platform
6 min read Video streaming is one of the most infrastructure-intensive system design problems. YouTube streams 1 billion hours of video per day. Read article
System Design
System Design: Chat System (WhatsApp / Messenger Scale)
7 min read A chat system is a perennial system design interview question. It requires you to reason about real-time communication, persistent storage, Read article
System Design
System Design: Twitter / Social Media Feed
6 min read Designing a social media feed is one of the most nuanced system design problems you’ll encounter in interviews. It looks Read article
AI/ML Interview Questions
Bias-Variance Tradeoff: Underfitting, Overfitting, and How to Fix Both
5 min read The bias-variance tradeoff is one of the first concepts asked in any machine learning interview. It underpins model selection, regularization, Read article