ADevGuide Archives
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How Logging Works in Backend Systems
Series: Practical Backend Engineering
Learn how backend logging works, including log levels, structured logs, correlation IDs, security, and production debugging.
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What Is a Message Queue? Simple Explanation with Examples
Series: Practical Backend Engineering
Learn what a message queue is, how producers and consumers work, and when to use RabbitMQ, SQS, or Kafka for async processing.
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What Is a Single Point of Failure (SPOF)?
Series: System Design Foundations
Learn what a single point of failure (SPOF) is, why it brings down entire systems, and how to eliminate it with redundancy and failover.
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What Is High Availability? A Beginner's Guide
Series: System Design Foundations
Learn what high availability means, how redundancy and failover work, and why uptime percentages like 99.9% matter for modern systems.
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What Is a Reverse Proxy? How It Works (For Beginners)
Series: System Design Foundations
What is a reverse proxy? Learn how it routes traffic, hides your origin, handles SSL termination, and differs from a forward proxy.
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What Is a CDN? How Content Delivery Networks Work
Series: System Design Foundations
What is a CDN? Learn how content delivery networks cache content at edge servers, reduce latency, and protect your origin from traffic spikes.
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In-Memory Cache vs Distributed Cache Explained
Series: System Design Foundations
Compare in-memory cache vs distributed cache: speed, scalability, consistency, and when to choose Redis over a local cache.
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What Is Caching? Why It Improves Performance
Series: System Design Foundations
What is caching? Learn how caches work, cache hits/misses, TTL, and common strategies (browser, CDN, Redis) to speed up apps.
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What Are Sticky Sessions in Load Balancing? (Session Affinity)
Series: System Design Foundations
Sticky sessions (session affinity) keep a user on the same backend. Learn how they work, when to use them, and safer stateless alternatives.
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Horizontal vs Vertical Scaling Explained (Scale Out vs Up)
Series: System Design Foundations
Horizontal vs vertical scaling explained: scale up vs scale out, trade-offs for cost, availability, and performance, plus real examples to choose confidently.
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What Is Load Balancing and How It Works
Series: System Design Foundations
What is load balancing? Learn how load balancers work, key algorithms, health checks, and Layer 4 vs Layer 7 trade-offs.
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What Is Scalability? A Beginner's Guide for Developers
Series: System Design Foundations
Learn what scalability means in software development, why it matters, and how vertical vs horizontal scaling work - with real-world examples.
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What Is Database Connection Pooling and Why It Matters
Series: Database Fundamentals
Learn what database connection pooling is, how it works under the hood, and why it is essential for building performant, scalable backend applications.
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How ORMs Work Internally: A Simple Explanation
Series: Database Fundamentals
Learn how Object-Relational Mappers work under the hood - from query building and identity maps to lazy loading and the N+1 problem.
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What Is a Database Transaction? Step-by-Step Guide
Series: Database Fundamentals
Learn what a database transaction is, how BEGIN, COMMIT, and ROLLBACK work, and when to use savepoints with clear SQL examples.
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ACID Properties Explained: Atomicity, Consistency, Isolation, and Durability
Series: Database Fundamentals
Learn what ACID properties mean in databases. Understand atomicity, consistency, isolation, and durability with simple examples and real-world use cases.
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Database Normalization Explained: 1NF, 2NF, and 3NF with Examples
Series: Database Fundamentals
Learn database normalization step by step. Understand 1NF, 2NF, and 3NF with clear table examples and how each normal form reduces redundancy.
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Basic SQL Queries Every Developer Must Know
Series: Database Fundamentals
Learn the essential SQL queries every developer needs: SELECT, WHERE, JOIN, GROUP BY, INSERT, UPDATE, and DELETE with real examples.
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What Are Database Indexes? How They Improve Performance
Series: Database Fundamentals
Learn what database indexes are, how they speed up SQL queries, and when to use single, composite, and covering indexes to improve performance.
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Primary Key vs Foreign Key Explained with Examples
Series: Database Fundamentals
Primary key vs foreign key explained with SQL examples, core differences, and best practices to design reliable relational database schemas.
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SQL vs NoSQL: Complete Guide to Differences, Use Cases, and Examples
Series: Database Fundamentals
Learn the key differences between SQL and NoSQL databases, their use cases, advantages, and when to choose each for your projects with practical examples.
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Relational Databases Explained: Tables, Rows, and Keys
Series: Database Fundamentals
Learn relational databases: tables, rows, columns, and keys - with practical SQL examples and clear explanations for beginners.
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REST API Error Handling Best Practices: Beginner Guide
Series: API and Backend Basics Series
Master REST API error handling with best practices for status codes, consistent payloads, retries, observability, and secure production APIs.
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What Is CORS? Complete Beginner Explanation
Series: API and Backend Basics Series
Learn what CORS is, why browsers block cross-origin requests, how preflight works, and which headers fix CORS errors safely.
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What Is Agentic AI? The Next Evolution After ChatGPT
Series: AI Engineering & Machine Learning Series
Learn what agentic AI is, how it differs from ChatGPT, how AI agents work, and why this shift matters for developers.
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How JWT Works: Step-by-Step Guide for Beginners
Series: API and Backend Basics Series
Learn how JWT works step by step with header, payload, signature, expiry, validation, and real API authentication flows.
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Java String Quiz: 16 MCQ Questions with Answers
Series: Java Interview & Problem Solving Series
Test your Java String knowledge with 16 MCQ questions and answers covering String, StringBuilder, StringBuffer, and SCP basics.
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Reverse Integer in Java: Simple Explanation and Code
Series: Java Interview & Problem Solving Series
Learn how to reverse an integer in Java without using built-in APIs, with a simple code example and step-by-step explanation.
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Kids With the Greatest Number of Candies: LeetCode Java Solution
Series: Java Interview & Problem Solving Series
Solve Kids With the Greatest Number of Candies in Java with a simple LeetCode approach, explanation, constraints, and example walkthrough.
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Reverse Words in a String III: LeetCode Java Solution
Series: Java Interview & Problem Solving Series
Solve Reverse Words in a String III in Java with a clean LeetCode approach, example walkthrough, constraints, and test cases.
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Merge Strings Alternately: LeetCode Java Solution
Series: Java Interview & Problem Solving Series
Solve Merge Strings Alternately in Java with a simple LeetCode approach, step-by-step explanation, constraints, and sample test cases.
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Robot Return to Origin: LeetCode Java Solution
Series: Java Interview & Problem Solving Series
Solve Robot Return to Origin in Java with a simple LeetCode approach, move-count logic, constraints, and example walkthrough.
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Singleton Pattern in Java: Explanation and Examples
Series: Java Design Patterns Series
Learn the Singleton pattern in Java with common implementations, thread-safety trade-offs, and practical examples you can reuse.
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SOLID Principles in Java: Explained with Examples
Series: Java Design Patterns Series
Learn SOLID principles in Java with practical examples for SRP, OCP, LSP, ISP, and DIP to write cleaner, maintainable code.
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Is Java Pass by Value or Pass by Reference?
Series: Java Interview & Problem Solving Series
Understand why Java is pass by value with clear examples for primitives, objects, and collections, plus the common interview trap.
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Java Regex Quiz: 20 MCQ Questions with Answers
Series: Java Interview & Problem Solving Series
Test your Java regex knowledge with 20 MCQ questions and answers covering Pattern, Matcher, syntax basics, and common matching rules.
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Java Interfaces Explained: How to Code to an Interface
Series: Java Interview & Problem Solving Series
Learn Java interfaces with clear examples and understand what 'code to an interface' means for flexibility, testing, and cleaner design.
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What Is Google AI Studio? Complete Guide for Developers
Series: AI Engineering & Machine Learning Series
Learn what Google AI Studio is, how it compares with Gemini and Vertex AI, and how to use prompts, tools, and API keys effectively.
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What Is Google Stitch? Guide to Google's AI UI Tool
Series: AI Engineering & Machine Learning Series
Learn what Google Stitch is, how it turns prompts into UI designs and frontend code, and where it fits in real product workflows.
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What Are Agent Skills? How Claude Skills Work
Series: AI Engineering & Machine Learning Series
Learn what Agent Skills are in Claude, how skill packages work, and how to design reusable, safe capabilities for modern AI agents.
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What Is MCP (Model Context Protocol)? Complete Guide
Series: AI Engineering & Machine Learning Series
Learn what MCP is, how Model Context Protocol works, and how it differs from APIs, RAG, agents, and function calling.
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Claude Code Subagents: What They Are and How They Work
Series: AI Engineering & Machine Learning Series
Learn what Claude Code subagents are, how delegation works, and how to configure tools, models, and permissions for focused workflows.
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Builder Pattern in Java: Explanation and Example
Series: Java Design Patterns Series
Learn the Builder pattern in Java with a clear example, method chaining, immutable objects, advantages, and common trade-offs.
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Composite Pattern in Java: Explanation and Example
Series: Java Design Patterns Series
Learn the Composite pattern in Java with a clear tree-structure example, uniform object handling, advantages, and common pitfalls.
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Factory Pattern in Java: Explanation and Example
Series: Java Design Patterns Series
Learn the Factory pattern in Java with a clear example, object creation flow, benefits, trade-offs, and when to use it.
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Factory Method Pattern in Java: Explanation and Example
Series: Java Design Patterns Series
Learn the Factory Method pattern in Java with a clear example, subclass-based creation, benefits, trade-offs, and use cases.
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Prototype Pattern in Java: Explanation and Example
Series: Java Design Patterns Series
Learn the Prototype pattern in Java with cloning examples, shallow vs deep copy, benefits, pitfalls, and practical use cases.
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How to Dockerize a Java Application with Maven and Dockerfile
Series: DevOps & Developer Tooling Series
Learn how to dockerize a Java application with Maven and a Dockerfile using a simple multi-stage build and common Docker commands.
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40 Agile Scrum Interview Questions and Answers
Series: Agile & Software Engineering Career Series
Prepare with 40 Agile Scrum interview questions and answers covering roles, ceremonies, sprints, backlog management, velocity, and burn charts.
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Spring Annotations Cheat Sheet: Core, MVC, and Boot
Series: CheatSheets
Use this Spring annotations cheat sheet to review core, MVC, Boot, and conditional annotations with short explanations and practical context.
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Adapter Design Pattern in Java: Explanation and Example
Series: Java Design Patterns Series
Learn the Adapter design pattern in Java with class and object adapter examples, use cases, pitfalls, and real-world analogies.
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Abstract Factory Pattern in Java: Explanation and Example
Series: Java Design Patterns Series
Learn the Abstract Factory pattern in Java with a clear example, object families, advantages, trade-offs, and when to use it.
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Cookies vs Local Storage vs Session Storage Explained
Series: API and Backend Basics Series
Learn cookies vs local storage vs session storage with security, expiry, size limits, and real frontend/backend examples.
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Basic Linux Commands for Developers: Command Cheat Sheet
Series: DevOps & Developer Tooling Series
Learn basic Linux commands every developer should know for navigation, files, processes, permissions, search, and everyday terminal work.
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Top Spring Boot Interview Questions and Answers
Series: Spring Boot Mastery Series
Prepare with top Spring Boot interview questions and answers covering auto-configuration, starters, Actuator, dependency injection, and REST APIs.
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Vertical vs Horizontal Sharding: Key Differences Explained
Series: Database Scalability Series
Compare vertical vs horizontal sharding with clear examples, trade-offs, and guidance on when each database scaling strategy fits best.
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Regular Expressions in Java: Complete Guide with Examples
Series: Java Interview & Problem Solving Series
Learn regular expressions in Java with clear syntax, Pattern and Matcher examples, common metacharacters, and practical regex use cases.
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Tomcat vs JBoss: Differences, Use Cases, and Which to Choose
Series: Java Interview & Problem Solving Series
Compare Tomcat vs JBoss across Java EE support, performance, deployment complexity, and when to choose each server in real projects.
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JWT vs Session Authentication: Complete Comparison
Series: API and Backend Basics Series
Learn JWT vs session authentication with security, scalability, revocation, cookies, refresh tokens, and real API use cases.
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Authentication vs Authorization: What's the Difference?
Series: API and Backend Basics Series
Learn authentication vs authorization with clear API examples, 401 vs 403, sessions, JWTs, and role checks in modern backends.
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What Is JSON? Why It's Used in APIs
Series: API and Backend Basics Series
Learn what JSON is, how its syntax works, and why APIs use it for fast, language-independent data exchange.
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HTTP Status Codes Explained (200, 404, 500 and More)
Series: API and Backend Basics Series
Learn HTTP status codes with real API examples of 200, 201, 301, 304, 400, 401, 403, 404, 429, 500, and 503.
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Git Cheat Sheet for Developers: Common Commands with Real Examples
Series: DevOps & Developer Tooling Series
Use this Git cheat sheet to learn the most useful Git commands for setup, commits, branches, remotes, undoing mistakes, and daily workflows.
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HTTP Methods Explained: GET vs POST vs PUT vs DELETE
Series: API and Backend Basics Series
Learn HTTP methods with real examples of GET, POST, PUT, PATCH, and DELETE, plus safety, idempotency, caching, and API design rules.
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What Is NemoClaw? How to Use NVIDIA's Secure OpenClaw Stack
Series: AI Engineering & Machine Learning Series
Learn what NVIDIA NemoClaw is, how it secures OpenClaw with OpenShell, and how to install, onboard, monitor, and run a sandboxed AI agent.
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Cursor Skills vs Rules vs Subagents: Complete Guide for AI Development
Series: AI Development Tools
Master Cursor's Skills, Rules, and Subagents. Learn what they are, when to use each, and how they compare for AI-powered coding workflows.
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What Is REST API? Beginner's Guide with Examples
Series: API and Backend Basics Series
Understand what a REST API is, how resources, methods, status codes, and stateless requests work, with practical backend examples.
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How APIs Work: A Simple Guide for Beginners
Series: Internet and Web Foundations Series
Learn how APIs work end to end: requests, responses, authentication, status codes, versioning, and practical backend patterns for beginners.
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Perforce MCP Server: AI-Powered Version Control for AI Agents
Series: DevOps & Developer Tooling Series
Learn how to integrate Perforce with VS Code, Claude, and AI assistants using the MCP Perforce Server. A complete guide to AI-powered version control workflows.
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What is OpenClaw? The Complete Personal AI Assistant Platform Guide
Series: AI Engineering & Machine Learning Series
Learn about OpenClaw, the open-source local-first AI assistant connecting Claude, GPT, and LLMs to WhatsApp, Telegram, Slack, Discord, and more channels.
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An Easy Step-By-Step Guide to Changing Server Port in a Spring Boot Application [4 Ways]
Series: Spring Boot Mastery Series
Learn 4 ways to change server port in Spring Boot: application properties, YAML config, command-line arguments, and programmatic setup with code examples.
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Monolith vs Microservices: Pros, Cons, and When to Choose
Series: Internet and Web Foundations Series
Understand monolith vs microservices architecture. Learn pros, cons, real-world examples from Netflix and Amazon, and when to use each approach.
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Application Server vs Web Server: Key Differences Explained
Series: Internet and Web Foundations Series
Understand application server vs web server with clear architecture patterns, Java and .NET examples, and when to use each in production.
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What Is a Web Server? How Nginx and Apache Work
Series: Internet and Web Foundations Series
Learn what a web server is and how Nginx and Apache handle HTTP requests, static files, reverse proxying, and production traffic.
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What Is Client-Server Architecture? Beginner Guide
Series: Internet and Web Foundations Series
Learn client-server architecture with clear request-response flow, tiers, scaling patterns, and practical backend design examples for beginners.
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How the Internet Works: Simple Explanation for Developers
Series: Internet and Web Foundations Series
Learn how the internet works end to end: packets, ISPs, routers, DNS, TCP/TLS, and CDNs, with practical debugging insights for developers.
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What Happens When You Type a URL? Step-by-Step Explained
Series: Internet and Web Foundations Series
Understand what happens when you type a URL: browser parsing, DNS lookup, TCP/TLS handshakes, HTTP flow, rendering, and debugging tips.
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TCP vs UDP Explained Clearly with Real Examples
Series: Internet and Web Foundations Series
Learn TCP vs UDP with real examples, packet flow, reliability trade-offs, and a practical decision framework for backend systems.
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How DNS Works: Complete Beginner Explanation
Series: Internet and Web Foundations Series
Learn how DNS works from browser query to authoritative answer, including records, caching, TTL, and practical troubleshooting steps.
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HTTP vs HTTPS: What's the Difference? (Beginner's Guide)
Series: Internet and Web Foundations Series
Learn HTTP vs HTTPS with clear examples: encryption, TLS certificates, integrity, authentication, SEO impact, performance, and migration best practices.
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System Design Interview: Notification System CheatSheet
Series: CheatSheets
Use this notification system design interview cheat sheet to remember queue patterns, retries, channel routing, and performance trade-offs.
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System Design Interview: Rate Limiter CheatSheet
Series: CheatSheets
Use this rate limiter system design interview cheat sheet to recall algorithms, Redis patterns, edge cases, and scaling math in minutes.
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System Design Interview: Twitter News Feed CheatSheet
Series: CheatSheets
Prepare faster with a Twitter news feed system design interview cheat sheet covering fan-out choices, feed ranking, caching, and trade-offs.
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System Design Interview: URL Shortener CheatSheet
Series: CheatSheets
Crack the URL shortener system design interview with this cheat sheet on APIs, Base62 keys, storage estimates, caching, and follow-up answers.
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What Is Hashing? Why It Matters in Modern Software Architecture
Series: Database Scalability Series
Learn hashing in software architecture: data distribution, cache keys, security, consistency, and performance trade-offs used in real production systems.
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System Design Interview: Ultimate Cheatsheet to Crack Any Round
Series: CheatSheets
Master your next system design interview with this practical cheatsheet covering requirements, architecture, scaling math, trade-offs, security, and follow-ups.
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What is Database Sharding? A Complete Guide with Real-World Examples
Series: Database Scalability Series
Learn what database sharding is, how it scales applications like Instagram, and explore key strategies like horizontal partitioning with real-world examples.
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System Design Interview: Distributed Cache Like Redis/Memcached
Series: System Design Interview Series
Master the distributed cache system design interview. Learn consistent hashing, eviction policies (LRU/LFU), and how to scale like Redis and Memcached.
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System Design Interview: Design a Rate Limiter
Series: System Design Interview Series
Master the rate limiter system design interview. Explore token bucket, leaky bucket algorithms, distributed rate limiting with Redis, and race conditions.
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System Design Interview: Design WhatsApp Chat System
Series: System Design Interview Series
Learn to design a scalable chat system like WhatsApp. Covers real-time messaging, WebSocket, last seen details, and end-to-end encryption.
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System Design Interview: Design Twitter News Feed
Series: System Design Interview Series
Master the Twitter system design interview. Learn fanout patterns, timeline generation, hybrid approach, and scaling for 300M active users.
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System Design Interview: Design a URL Shortener
Series: System Design Interview Series
Master the URL Shortener system design interview. Learn about Base62 encoding, Key Generation Service (KGS), data scale, and handling billions of clicks.
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System Design Interview: Design Instagram Feed
Series: System Design Interview Series
Master the Instagram Feed system design interview. Learn feed generation, fan-out service, pull vs push models, and scaling for millions of users.
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System Design Interview: Basic Notification System (Email & Push)
Series: System Design Interview Series
Master the notification system design interview. Learn how to build scalable email and push notification delivery, handle retries, and optimize for reliability.
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System Design Interview: Collaborative Document Editor Like Google Docs
Series: System Design Interview Series
Master the collaborative document editor system design interview. Learn operational transformation, CRDTs, conflict resolution, and scalability patterns.
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API Rate Limiting: Complete Guide with Spring Boot Implementation
Series: Spring Boot Mastery Series
Learn API rate limiting strategies, algorithms, and implementation using Spring Boot. Discover how companies like Twitter and GitHub protect their APIs.
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XGBoost (eXtreme Gradient Boosting): A Complete Guide for Beginners
Series: AI Engineering & Machine Learning Series
Learn XGBoost, the machine learning algorithm dominating Kaggle competitions. Real-world examples from Netflix, Airbnb, and fraud detection systems.
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Retrieval-Augmented Generation (RAG) for Beginners: A Complete Guide
Series: AI Engineering & Machine Learning Series
Learn what Retrieval-Augmented Generation (RAG) is, how it works, and why it's revolutionizing AI applications in enterprise search and customer support.
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Spring Boot @Valid vs @Validated: An Easy In-Depth Comparison
Series: Spring Boot Mastery Series
Today we will be talking about “Spring Boot @Valid vs @Validated”. When it comes to building web applications, it’s essential to handle input
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13 Most Basic Docker Commands Every Developer Should Know
Series: DevOps & Developer Tooling Series
In 2020, every developer is expected to know at least some of the Most Basic Docker Commands. Developers should know how to write a dockerfile and must be able