Design a CDN (Content Delivery Network)
6 min read Design a Content Delivery Network like Cloudflare, Akamai, or AWS CloudFront. A CDN is infrastructure that most large-scale systems depend […] Read article
System Design
AI/ML Interview Questions
How Transformer Models Work: Attention Mechanism Explained
6 min read Transformers are the architecture behind GPT, BERT, Claude, and every other major language model. Understanding how they work — especially Read article
AI/ML Interview Questions
Fine-tuning LLMs vs Training from Scratch: When and How
6 min read One of the most common LLM interview questions in 2026: “Would you fine-tune a model or train from scratch?” Almost Read article
System Design
Design a Distributed ID Generator (Snowflake)
4 min read Design a distributed ID generation service. Every large-scale system needs unique IDs — for database rows, events, messages, and transactions. Read article
AI/ML Interview Questions
How to Choose Between Machine Learning Models
5 min read One of the most common ML interview questions isn’t about a specific algorithm — it’s “how do you decide which Read article
AI/ML Interview Questions
Train/Test/Validation Split: The Right Way and Common Mistakes
6 min read Train/test/validation splits are foundational — and routinely misunderstood. The most common mistake in applied ML is using the test set Read article
System Design
Design Google Maps / Navigation System
6 min read Design a navigation system like Google Maps. This problem combines geospatial data at scale, graph algorithms, real-time data ingestion, and Read article
System Design
Design a Hotel / Airbnb Reservation System
5 min read Design a hotel or vacation rental reservation system like Booking.com or Airbnb. The core challenge isn’t the search UI — Read article
System Design
Design a Proximity Service (Yelp / Nearby Search)
5 min read Design a proximity service like Yelp’s “restaurants near me” or Google Maps’ nearby search. The core challenge is geospatial indexing Read article
AI/ML Interview Questions
Feature Selection and Dimensionality Reduction: PCA, Lasso, and Tree Importance
6 min read Feature selection and dimensionality reduction are how you fight the curse of dimensionality — the phenomenon where models trained on Read article
AI/ML Interview Questions
Handling Imbalanced Datasets in Machine Learning
5 min read Imbalanced datasets — where one class dramatically outnumbers another — are the norm in production ML, not the exception. Fraud Read article
System Design
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
AI/ML Interview Questions
Cross-Validation Strategies: K-Fold, Time Series, and Nested CV
5 min read Cross-validation is how you estimate a model’s generalization performance before deploying it. Getting this wrong — especially data leakage — 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
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