#System Design

10MB images upload fine but 2GB videos timeout. Chunked uploads, presigned URLs, and retry logic for robust file upload systems.

Sending one notification is easy. As notifications scale up, preventing duplicates, respecting preferences, and handling retries becomes a completely different engineering problem.

Started with SQL LIKE, hit its limits, moved to Elasticsearch, and got shocked by operational costs. The real trade-offs of search systems.

Integrating a payment API is just the beginning. Idempotency, refund flows, and double-charge prevention make payment systems genuinely hard.

Building a feed like Instagram sounds simple until a user with 1M followers posts. Understanding push vs pull models and fan-out strategies.

1:1 chat is straightforward, but group chat, read receipts, and offline messages turn it into a completely different beast.

A URL shortener sounds trivial until you face hash collisions, expiration policies, and redirect latency. A microcosm of system design.

My app made users wait 3 seconds after clicking 'Sign Up' just to send a welcome email. If the email server failed, the sign-up failed too. I share how I used a Message Queue (BullMQ) to decouple these processes, explained with a 'Restaurant Order Ticket' analogy.

Without a Rate Limiter, your own users can accidentally DDOS your server. I compare core algorithms like Token Bucket, Leaky Bucket, and Sliding Window, and show how to implement a distributed Rate Limiter using Redis and Lua Scripts.

Why you can't have it all. Consistency vs Availability in the face of Partitions. Explaining CP (MongoDB) vs AP (Cassandra) and the extended PACELC theorem.

Why API Gateway is essential in Microservices Architecture. Detailed comparison of Kong vs. Nginx vs. AWS API Gateway, deep dive into Rate Limiting algorithms, GraphQL integration strategies, and ensuring Observability.

When Scale-Up fails, Scale-Out is the answer. Vertical vs Horizontal Partitioning, Shard Key selection strategies (Geo vs Hash), and the complexity of Distributed Transactions.

Round Robin, Least Connections, IP Hash explained. The difference between L4 (Layer 4) and L7 (Layer 7) load balancing, and how to configure Nginx as a Reverse Proxy.

DDoS attacks are getting smarter and larger. This guide breaks down the anatomy of an attack, distinguishing between volumetic (L3/L4) and application layer (L7) assaults. Learn how enterprise defenses like Anycast networks, scrubbers, and intelligent rate limiting protect modern infrastructure.

DDD is not just about entities and repositories. It's a strategic approach to tackling complex software problems. Learn how Ubiquitous Language, Bounded Contexts, and Aggregates can help you model the real world and align your software architecture with business goals. We also explore Event Storming and Strategic Design.

In complex domains, using a single data model for both reading and writing can lead to performance bottlenecks and messy code. Learn how CQRS (Command Query Responsibility Segregation) coupled with Event Sourcing can decouple your architecture, improve scalability, and simplify domain logic.

Stop cascading failures in distributed systems. Understand the 3 states of a Circuit Breaker, the dangers of infinite retries, and how to implement Bulkheads, Rate Limiters, and Graceful Degradation using Resilience4j and Istio.

Why would Netflix intentionally shut down its own production servers? Explore the philosophy of Chaos Engineering, the Simian Army, and detailed strategies like GameDays and Automating Chaos to build resilient distributed systems.

Where should you place your cache? A deep dive into Cache-Aside, Read-Through, Write-Back, and Write-Around patterns. Includes advanced topics like Cache Penetration, Breakdown, Avalanche, and a comparison of Distributed vs Local Caching.