Ajit - Get SDE Ready

Menu close menu icon Introduction to High-Level System Design What is System Design? Difference Between HLD and LLD Key Considerations in HLD System Design Fundamentals Functional vs. Non-Functional Requirements Scalability, Availability, and Reliability Latency and Throughput Considerations Load Balancing Strategies Architectural Patterns Monolithic vs. Microservices Architecture Layered Architecture Event-Driven Architecture Serverless Architecture Model-View-Controller (MVC) Pattern CQRS (Command Query Responsibility Segregation) Scaling Strategies Vertical Scaling vs. Horizontal Scaling Sharding and Partitioning Data Replication and Consistency Models Load Balancing Strategies CDN and Edge Computing Database Design in HLD SQL vs. NoSQL Databases CAP Theorem and its Impact on System Design Database Indexing and Query Optimization Database Sharding and Partitioning Replication Strategies API Design and Communication REST vs. GraphQL vs. gRPC Designing Scalable APIs Rate Limiting and Throttling Authentication & Authorization (OAuth, JWT) Caching Strategies Types of Caching Cache Invalidation Strategies Redis vs. Memcached Cache-Aside, Write-Through, and Write-Behind Strategies Message Queues and Event-Driven Systems Kafka vs. RabbitMQ vs. SQS Pub-Sub vs. Point-to-Point Messaging Handling Asynchronous Workloads Eventual Consistency in Distributed Systems Security in System Design Encryption (AES, RSA, TLS) API Security Best Practices Secure Data Storage and Access Control DDoS Protection and Rate Limiting Observability and Monitoring Logging Strategies (ELK Stack, Prometheus, Grafana) API Security Best Practices Secure Data Storage and Access Control DDoS Protection and Rate Limiting Real-World System Design Case Studies Distributed locking (Locking and its Types) Memory leaks and Out of memory issues HLD of YouTube HLD of WhatsApp System Design Interview Questions Adobe System Design Interview Questions Top Atlassian System Design Interview Questions Top Amazon System Design Interview Questions Top Microsoft System Design Interview Questions Top Meta (Facebook) System Design Interview Questions Top Netflix System Design Interview Questions Top Uber System Design Interview Questions Top Google System Design Interview Questions Top Apple System Design Interview Questions Top Airbnb System Design Interview Questions Top 10 System Design Interview Questions Mobile App System Design Interview Questions Top 20 Stripe System Design Interview Questions Top Shopify System Design Interview Questions Top 20 System Design Interview Questions Top Advanced System Design Questions Most-Frequented System Design Questions in Big Tech Interviews What Interviewers Look for in System Design Questions Critical System Design Questions to Crack Any Tech Interview Top 20 API Design Questions for System Design Interviews Top 10 Steps to Create a System Design Portfolio for Developers close menu icon IRCTC System Design: Scalable Train Ticket Booking Architecture The Indian Railway Catering and Tourism Corporation (IRCTC) powers one of the world’s largest online train ticket booking platforms. Designing a scalable train ticket booking system architecture requires balancing real-time seat availability, dynamic scaling for peak hours, and stringent transactional integrity. Whether you’re building a similar platform or preparing for system design interviews, this crash course in scalable system design can help you master the fundamentals.To get started with core principles, check out our comprehensive Crash Course on System Design and fast-track your learning.Key Goals and Functional RequirementsEvery train booking platform must handle user searches, bookings, cancellations, and additional services seamlessly. The IRCTC design ensures:Train and station listing across India with route and schedule details.Real-time seat availability with the option to view nearby dates (+3/–3 days).Class selection (1AC, 2AC, 3AC, Sleeper, General) with transparent fare breakdown.Tatkal booking support for next-day travel, scaling to millions of concurrent users at 10 AM and 11 AM.Fair berth allocation prioritizing senior citizens, single women, families, and berth preferences.Multiple payment methods (UPI, net banking, cards, wallets) to ensure a smooth transaction.Automated notifications for PNR status via SMS and email.Onboard services booking (meals, bedrolls, wheelchair assistance).For a deep dive into algorithmic challenges like real-time availability checks, our Master DSA Course covers the data structures you need to know.Core Non-Functional RequirementsBeyond features, the platform must excel in:Scalability & PerformanceHandle millions of requests per second during peak Tatkal windows.Auto-scale infrastructure up at 10 AM and 11 AM and scale down afterward.Transactional Integrity (ACID Compliance)No duplicate or failed bookings.Payments processed only after seat confirmation.High Availability & Fault ToleranceActive-passive database replication with automated failover.Distributed caching (Redis cluster) to offload read traffic.Partial Booking SupportConfirm available seats; move the rest to RAC or waitlist.Understanding these constraints is critical. If you’re also tackling real-world projects or interviews, explore our Essential DSA & Web Dev Courses for Programmers to solidify your foundation.Critical Design ConsiderationsMicroservices and API GatewayAPI Gateway routes requests to microservices:/trains/search → Train Service/tickets/book → Booking Service/tickets/{pnr}/status → Status ServiceMessaging Queues (booking_queue, payment_queue, notification_queue) for asynchronous processing.To master microservices patterns and messaging, review our Master DSA, Web Dev & System Design Program for in-depth tutorials.Caching and Load BalancingWrite-Through vs. Write-Behind cache strategies to maintain consistency and performance.Cache Invalidation on seat booking to ensure fresh data:Invalidate the entire key (e.g., seat_availability:12001:1)Or update specific fields (HSET seat_availability:12001:1 A1 false) For hands-on caching examples and real-time system design tips, our Crash Course on System Design includes dedicated modules on Redis and load balancing.Capacity Planning and Traffic Estimates5 billion page views per month20 million tickets processed monthly5 000 railway stations across IndiaDynamic scaling and efficient caching reduce database load, ensuring sub-second response times even during the daily Tatkal surge. API ReferenceSearch & AvailabilityGET /trains/search Query parameters: source, destination, date, class, quota Returns up-to-date train schedules and seat counts.GET /trains/{train_id}/availability Provides confirmed seats, RAC, and waitlist numbers.Booking & CancellationPOST /tickets/book Body includes passenger details, berth preferences, class, quota, and payment method.POST /tickets/{ticket_id}/cancel Processes refunds per IRCTC policy. Preparing for backend roles? Boost your algorithmic skills with our Top 20 DSA Interview Questions You Need to Know and get interview-ready.Handling Partial Bookings and FairnessAuto-selection confirms available seats, allocates RAC or waitlist as needed.Quota-based allocationSenior citizens → lower berthsSingle women → side berths or grouping with other womenStrengthen your understanding of reservation algorithms by exploring our Top Amazon DSA Interview Questions Prep Guide 2025 and Top Meta Facebook DSA Interview Questions.Sharding Strategy for ScalabilityHorizontal sharding by train_id, user_id, or booking_id.Directory-based sharding with a shard manager for efficient routing.Dive into distributed database patterns in our Data Science Course to learn how analytics can inform shard key selection.Implementing Fault ToleranceDatabase replication (primary-replica) with automatic failover.Load balancers distribute traffic across microservice instances.Automated backups and distributed caching ensure data durability.If you’re aiming for SDE interviews, check out our Top Netflix DSA Interview Questions 2025 Prep Guide and Top Atlassian DSA Interview Questions Solutions 2025 Guide.ConclusionDesigning a scalable, high-availability ticket booking platform like IRCTC demands a solid grasp of microservices, caching strategies, ACID transactions, and dynamic scaling. By blending theory with hands-on practice from our courses—whether you’re reinforcing DSA fundamentals, mastering web development, or tackling system design challenges—you’ll be equipped to build robust platforms and excel in technical interviews. How do I master the core data structures and algorithms for technical interviews? Start by building a strong foundation in arrays, linked lists, trees, graphs, sorting and searching techniques. Our DSA course offers hands‑on coding challenges, step‑by‑step explanations, and mock interview questions to help you ace your next interview. What’s the fastest way to become a proficient full‑stack web developer? Focus on both front‑end and back‑end technologies—HTML, CSS, JavaScript frameworks, RESTful APIs, and databases. Enroll in our Web Development course to learn modern stacks through real projects and mentorship from industry experts. Should I combine system design principles with DSA practice or tackle them separately? Integrating design patterns and algorithmic thinking accelerates your learning curve and prepares you for senior roles. Our Design + DSA Combined course merges system design workshops with algorithm deep‑dives for a cohesive experience. Which program covers advanced system design alongside web development and DSA? For a comprehensive curriculum that spans data structures, web frameworks, and large‑scale system architecture, check out our Master DSA, Web Dev & System Design course. It’s tailored for those aiming at high‑impact engineering roles. How can I apply data science techniques to solve real‑world problems? Learn how to preprocess data, build predictive models, and visualize insights using Python and machine learning libraries. Our Data Science course guides you through end‑to‑end projects and case studies to make your portfolio stand out. Start by building a strong foundation in arrays, linked lists, trees, graphs, sorting and searching techniques. Our DSA course offers hands‑on coding challenges, step‑by‑step explanations, and mock interview questions to help you ace your next interview.Focus on both front‑end and back‑end technologies—HTML, CSS, JavaScript frameworks, RESTful APIs, and databases. Enroll in our Web Development course to learn modern stacks through real projects and mentorship from industry experts.Integrating design patterns and algorithmic thinking accelerates your learning curve and prepares you for senior roles. Our Design + DSA Combined course merges system design workshops with algorithm deep‑dives for a cohesive experience.For a comprehensive curriculum that spans data structures, web frameworks, and large‑scale system architecture, check out our Master DSA, Web Dev & System Design course. It’s tailored for those aiming at high‑impact engineering roles.Learn how to preprocess data, build predictive models, and visualize insights using Python and machine learning libraries. Our Data Science course guides you through end‑to‑end projects and case studies to make your portfolio stand out. This insightful blog post is authored by Ajit Pedha, who brings his expertise and deep understanding of the topic to provide valuable perspectives. Ajit Pedha Full stack web developer | .Net Core, Azure, Angular, Devops, SQL, AI enthusiast Got Confusion ? Accelerate your Path to a Product based Career Boost your career or get hired at top product-based companies by joining our expertly crafted courses. Gain practical skills and real-world knowledge to help you succeed. Explore our flagship courses Reach Out Now If you have any queries, please fill out this form. We will surely reach out to you. Contact Email Reach us at the following email address. arun@getsdeready.com Phone Number You can reach us by phone as well. +91-97737 28034 Our Location Rohini, Sector-3, Delhi-110085

Author: Ajit

IRCTC High-Level System Design

From Upload to Play: Understanding YouTube’s Scalable Architecture

Longest Consecutive Subsequence: O(n) Algorithm Optimization

Quick Links

Quick Links

Social Media

Quick Links

Quick Links

Social Media

Hi Instagram Fam! Get a FREE Cheat Sheet on System Design.

Hi LinkedIn Fam! Get a FREE Cheat Sheet on System Design

Loved Our YouTube Videos? Get a FREE Cheat Sheet on System Design.

Hi Instagram Fam!
Get a FREE Cheat Sheet on System Design.

Hi LinkedIn Fam!
Get a FREE Cheat Sheet on System Design