Thoughts on backend engineering, systems, and craft.

Mastering the Two Pointers Pattern in Java

Two pointers is one of the most versatile DSA patterns. Here's every variant — opposite ends, fast-slow, and multi-array — with Java solutions and when to reach for each.

Jun 8, 20256 min

System DesignRedisPostgreSQL

System Design: URL Shortener Like bit.ly

Designing a URL shortener end-to-end — Base62 encoding, hash collisions, database choice, caching layer, and how to handle 100M+ URLs at scale.

Jun 2, 20259 min

Featured

JPA N+1 Problem: How to Find and Fix It in Spring Boot

The N+1 query problem silently kills performance in Spring Boot apps. Here's how to detect it with Hibernate stats, and three strategies to eliminate it — JOIN FETCH, @EntityGraph, and projections.

JavaSpring BootJPA

May 22, 20257 min

System DesignRedisSpring Boot

Rate Limiter Design: Token Bucket vs Leaky Bucket vs Sliding Window

Designing a rate limiter from scratch — three algorithms compared, Redis-based distributed implementation, and how Spring Boot API Gateway handles it in practice.

May 15, 20258 min

Sliding Window Pattern: From Easy to Hard

Sliding window is the go-to pattern for subarray and substring problems. Here's the fixed-size and variable-size templates, plus the counter trick that solves 'at most K' problems.

May 8, 20256 min

Docker + Spring Boot: Production-Ready Setup

From a naive 900MB image to a lean 180MB multi-stage build — Dockerfile best practices, environment config, health checks, and Docker Compose for local dev.

DockerSpring BootJava

May 2, 20257 min

Binary Search: Beyond Sorted Arrays

Most people use binary search only on sorted arrays. But the real power is binary search on the answer space — solving problems in O(log n) that look like they need O(n) or brute force.

Apr 20, 20256 min

Redis Caching with Spring Boot: Real-World Patterns

Beyond @Cacheable — TTL strategies, cache-aside vs write-through, cache warming, and how to handle cache invalidation without shooting yourself in the foot.

RedisSpring BootJava

Apr 10, 20257 min

System DesignKafkaDistributed Systems

System Design: Distributed Message Queue from Scratch

Designing a Kafka-like message queue — partitioning, consumer groups, offset management, at-least-once vs exactly-once delivery, and where each guarantee breaks down.

Apr 3, 202510 min

Dynamic Programming: 5 Patterns That Cover 80% of Problems

Stop memorizing DP solutions. Learn these 5 patterns and you'll recognize DP problems on sight — with Java implementations for each.

Mar 25, 20259 min

Spring Boot + Kafka: Event-Driven Architecture in Practice

How I wired Kafka into a Spring Boot microservice — configuration, serialization, error handling, retries, dead letter topics, and the pitfalls that bit me in production.

JavaSpring BootKafka

Mar 14, 20258 min

System DesignMicroservicesArchitecture

Microservices vs Monolith: When to Split and When Not To

After building both, here's my honest take — microservices are not always better. The decision framework I use, the hidden costs nobody talks about, and when a modular monolith wins.

Mar 5, 20257 min

Graph Algorithms You Need for Coding Interviews (Java)

BFS, DFS, Dijkstra, Union-Find, and topological sort — the templates and problem-recognition patterns you need to solve graph problems under interview pressure.

Feb 20, 20259 min

Spring Boot Exception Handling: The Right Way

Stop returning 500s with stack traces. Here's a clean, centralized exception handling setup using @ControllerAdvice, custom exceptions, and structured error responses.

JavaSpring BootREST APIs

Feb 10, 20255 min

System DesignPostgreSQLDatabase

Database Sharding: Strategies and Trade-offs

When a single DB instance isn't enough — horizontal sharding strategies, choosing a shard key, cross-shard queries, and the rebalancing problem nobody warns you about.

Feb 3, 20258 min

Monotonic Stack: The Pattern That Solves Histogram Problems

Monotonic stack is one of those patterns that looks magical until you understand the invariant it maintains. Next greater element, largest rectangle in histogram, daily temperatures — all solved with the same idea.

Jan 22, 20256 min

JavaSpring BootSpring Security

Spring Security: OAuth2 + SSO Integration Deep Dive

Wiring OAuth2 login, SSO with LinkedIn and Google, custom JWT issuance after OAuth handshake, and the session vs stateless trade-off you need to make early.

Jan 12, 20258 min

Heap and Priority Queue: Solving Top-K Problems in Java

PriorityQueue in Java, max-heap vs min-heap, the K closest points trick, merge K sorted lists, and finding the Kth largest element — patterns and templates.

Jan 5, 20256 min

JavaMultithreadingCompletableFuture

Java Multithreading: CompletableFuture in Production

CompletableFuture patterns that actually appear in production code — parallel API calls, fan-out/fan-in, custom thread pools, timeout handling, and when to use Virtual Threads instead.

Dec 18, 20248 min

System Design: Search Autocomplete at Scale

Designing Google-style search autocomplete — Trie data structure, prefix frequency ranking, caching layers, and how to serve 10,000 suggestions/sec with sub-50ms latency.

System DesignTrieRedis

Dec 8, 20249 min