New content added weeklyLive
Master HLD with Adaptive AI.
Master HLD across 186 patterns - HLD - guided by Leyaa's adaptive intelligence.
32Topics
186Patterns
45hEst. duration
HLD Course
32 topics
Databases - SQL and Transactions
7 patterns
Monitoring and Observability
5 patterns
Microservices Infrastructure
5 patterns
API Design and Gateway
6 patterns
Non-Functional Requirements Framework
7 patterns
System Design Interview Approach
8 patterns
System Failures and Post-Mortems
5 patterns
Storage Systems
5 patterns
Bloom Filters and Probabilistic Data Structures
5 patterns
Caching
6 patterns
Content Delivery Network
5 patterns
Core Distributed Systems Concepts
8 patterns
Distributed Coordination
4 patterns
Consistent Hashing
5 patterns
Message Queues and Event Streaming
7 patterns
AI and ML System Design
8 patterns
Modern Infrastructure Design
6 patterns
Storage and Collaboration
5 patterns
Financial and Real-Time Systems
4 patterns
Infrastructure and Platform Systems
7 patterns
E-Commerce and Payments
5 patterns
Location and Mapping Systems
5 patterns
Social Media and Feed Systems
6 patterns
Search and Discovery
7 patterns
Video and Media Streaming
5 patterns
Communication and Messaging Systems
5 patterns
Rate Limiting
6 patterns
Networking and Protocols
7 patterns
Databases - NoSQL
6 patterns
Search and Indexing
5 patterns
Load Balancers
6 patterns
Unique ID Generation
5 patterns
Curriculum
Everything You'll Learn
Explore every pattern in the course.
HLD
32 topics · 186 patterns01
Databases - SQL and Transactions
7 patterns
ACID Properties - Atomicity, Consistency, Isolation, Durability Deep DiveDatabase Indexing - B-Tree, Hash Index, Composite Index DesignDatabase Replication - Primary-Replica, Multi-Primary PatternsDatabase Sharding Strategies - Range, Hash, Directory-BasedHow to Choose a Database - Decision Framework for InterviewsRead Replicas and CQRS Pattern for Read-Heavy SystemsWhy Relational Databases Dominate Transactional Systems
02
Monitoring and Observability
5 patterns
Alerting System Design - Threshold, Anomaly, Composite Alert PatternsDistributed Logging Architecture - Log Aggregation Pipeline DesignDistributed Tracing System - Trace Context Propagation Across ServicesMetrics Collection System Design - Push vs Pull Model Trade-offsSLO Error Budget Tracking - How Production Systems Measure Reliability
03
Microservices Infrastructure
5 patterns
API Gateway as Microservices Entry Point - BFF PatternBulkhead Pattern - Isolating Failures to Contain Blast RadiusCircuit Breaker Pattern - Preventing Cascade Failures Across ServicesMicroservices vs Monolith - When to Split and the Hidden CostsService Discovery - Client-Side vs Server-Side Patterns
04
API Design and Gateway
6 patterns
API Gateway Pattern - Auth, Rate Limiting, Routing, TransformationAPI Versioning Strategies - URL, Header, Content NegotiationGraphQL vs REST - Trade-offs for Different Query PatternsgRPC for Internal Service Communication - Protocol Buffers, StreamingIdempotency in APIs - Why It Is Critical for Payment and Retry SystemsREST API Design Principles - Resources, Methods, Status Codes, Pagination
05
Non-Functional Requirements Framework
7 patterns
Availability - Active-Active vs Active-Passive Failover PatternsDurability - How Systems Guarantee Data is Never LostObservability - Metrics, Logging, Tracing - The Three PillarsPerformance - P50 P95 P99 Latency and Why Averages LieReliability and Fault Tolerance - Designing for Failure Not IfScalability - Designing for 10x, 100x, 1000x Traffic Growth from Day OneSecurity Fundamentals - AuthN, AuthZ, Encryption at Rest and in Transit
06
System Design Interview Approach
8 patterns
Availability Numbers - What 99.9 vs 99.99 vs 99.999 Percent Means in PracticeBack-of-the-Envelope Estimation with Real Numbers - Servers, Storage, BandwidthClarifying Requirements - Functional vs Non-Functional Questions to AskCommon Mistakes Candidates Make in System Design InterviewsHow to Estimate QPS, DAU, Storage, and Bandwidth for Any SystemHow to Present Trade-offs and Justify Design Decisions to InterviewersHow to Structure Any System Design Answer in 45 MinutesWhy System Design Exists and What Single Machines Cannot Do
07
System Failures and Post-Mortems
5 patterns
AWS US-EAST-1 Outage - Cascading Failures and Blast Radius LessonsCloudflare Route Leak - How One Config Took Down the InternetFacebook October 2021 Outage - BGP Misconfiguration and Global RecoveryGitHub Database Failover Incident - What Went Wrong and PreventionHow to Write a Post-Mortem - Blameless Culture, Root Cause Analysis, Action Items
08
Storage Systems
5 patterns
Blob Store Design - S3-Like Object Storage Architecture End to EndBlock Storage vs Object Storage vs File Storage - When to Use WhichData Replication Strategies - Synchronous vs Asynchronous, Quorum WritesDistributed File System Design - Metadata Servers and Data NodesStorage Tiering - Hot, Warm, Cold, Archive and Cost Optimization
09
Bloom Filters and Probabilistic Data Structures
5 patterns
Bloom Filter Design - Bit Array, Hash Functions, False Positive RateBloom Filters in Real Systems - Cassandra, Redis, BigTable, ChromeCount-Min Sketch for Frequency Estimation at ScaleHyperLogLog for Cardinality Estimation - Counting Unique Users CheaplyWhy Bloom Filters and What Exact Lookup Cannot Afford at Scale
10
Caching
6 patterns
Cache Aside vs Read-Through vs Write-Through vs Write-BehindCache Eviction Policies - LRU, LFU, TTL, ARC and When to Use EachCache Stampede - Thundering Herd Problem and Prevention StrategiesCache Warming Strategies for High-Traffic System LaunchesDistributed Cache Design - Consistent Hashing for Cache Node AssignmentWhy Caching Exists and the Real Cost of Not Caching
11
Content Delivery Network
5 patterns
Cache Invalidation Strategies - TTL, Purge, Surrogate KeysCDN Architecture - Edge Nodes, Points of Presence, Origin Pull vs PushCDN for Video Streaming - Adaptive Bitrate and HLS Segment DeliveryMulti-CDN Strategy for Maximum Availability and Geo CoverageWhy CDN Exists and What Origin Servers Cannot Do Alone
12
Core Distributed Systems Concepts
8 patterns
CAP Theorem - Consistency, Availability, Partition Tolerance in Real SystemsClient-Server Architecture and Why It Is the Foundation of Every SystemConsistency Models - Strong, Eventual, Causal, Read-Your-Writes ExplainedLatency vs Throughput - The Core Trade-off Every Design Must BalancePACELC Theorem - Beyond CAP for Systems That Must Choose Under LatencyStateless vs Stateful Services - Design Implications at ScaleSynchronous vs Asynchronous Communication - When Each WinsVertical Scaling vs Horizontal Scaling - When Each Breaks and What to Do
13
Distributed Coordination
4 patterns
14
Consistent Hashing
5 patterns
Consistent Hashing for Database Sharding at ScaleConsistent Hashing in Distributed Caches - Redis Cluster, MemcachedHash Ring - Virtual Nodes, Token Assignment, Node Addition and RemovalRendezvous Hashing - Alternative Approach and Trade-offsWhy Consistent Hashing and What Modular Hashing Cannot Handle
15
Message Queues and Event Streaming
7 patterns
Dead Letter Queues and Retry Strategies for Failure HandlingEvent Sourcing and CQRS with Message QueuesKafka Architecture - Partitions, Consumer Groups, Offsets, Retention PolicyMessage Delivery Guarantees - At Most Once, At Least Once, Exactly OnceMessage Queue Design - Producers, Consumers, Brokers, PartitionsPub-Sub Pattern - Topics, Subscriptions, Fan-Out DesignWhy Async Messaging and What Synchronous Calls Cannot Handle
16
AI and ML System Design
8 patterns
Design a ChatGPT-Like System - LLM Serving, Context Window, Token StreamingDesign a Data Infrastructure for ML - Feature Store, Training Pipeline, RegistryDesign a Real-Time ML Inference System - Model Serving, Shadow Mode, RollbackDesign a Recommendation System - Collaborative Filtering, Embedding StorageDesign a Search Ranking System - Feature Store, Model Serving, A/B TestingDesign a Vector Database - Embedding Storage, ANN Search, HNSW IndexDesign an AI Code Assistant - RAG Architecture, Code Indexing, Latency BudgetDesign an LLM-Powered Customer Support Bot - Intent Classification, Fallback
17
Modern Infrastructure Design
6 patterns
Design a CI/CD Pipeline System - Build, Test, Deploy, Rollback, Artifact RegistryDesign a Code Deployment System - Blue-Green, Canary, Feature Flags, Rollback StrategyDesign a Multi-Tenant SaaS Platform - Isolation, Billing, Feature FlagsDesign a Real-Time Analytics Pipeline - Kafka, Flink, OLAP, DashboardWebhook Delivery System - Reliability, Retry, Ordering GuaranteesDesign an Event-Driven Architecture - Saga Pattern, Outbox Pattern, Idempotency
18
Storage and Collaboration
5 patterns
Design a Code Repository System - Diff, Branch, Merge, Pull RequestDesign a Web Crawler - Scheduler, Politeness Policy, Duplicate DetectionDesign Dropbox or Google Drive - File Sync, Chunking, Delta UploadDesign Google Docs - Collaborative Editing, Conflict Resolution, OT vs CRDTDesign Pastebin - Text Storage, Expiration, Analytics
19
Financial and Real-Time Systems
4 patterns
Design a Digital Wallet System - Double-Entry Ledger, Consistency, ReconciliationDesign a Fraud Detection System - Real-Time Scoring, Rule Engine, Feature StoreDesign a Real-Time Leaderboard - Sorted Sets, Redis, Ranking at ScaleDesign a Stock Exchange - Order Book, Matching Engine, Market Data Feed
20
Infrastructure and Platform Systems
7 patterns
Design a Distributed Cache - Consistent Hashing, Eviction, ReplicationDesign a Distributed Counter - Sharded Counters, CRDT for Eventual ConsistencyDesign a Distributed Message Queue - Kafka-Like Architecture End to EndDesign a Key-Value Store - Consistent Hashing, Vector Clocks, Gossip ProtocolDesign a Task Scheduler - Priority Queue, Cron, Distributed ExecutionDesign a URL Shortener - Encoding, Redirect, Analytics, Custom AliasDesign an API Rate Limiter - Algorithms, Distributed Counter, Edge Enforcement
21
E-Commerce and Payments
5 patterns
Design a Flash Sale System - Handling 10x Traffic Spike in 60 SecondsDesign a Payment Gateway like Razorpay or Stripe - Architecture, Webhook, RetryDesign a Payment System - Transaction Processing, Idempotency, SettlementDesign a Ticketing System like BookMyShow - Seat Locking, Concurrency, PaymentAmazon - Product Catalog, Search, Cart, Order Management Pipeline
22
Location and Mapping Systems
5 patterns
Design a Food Delivery System - Restaurant Discovery, Order Tracking, Driver AssignmentDesign a Real-Time Location Tracking System - GPS, WebSocket, Geo-indexingDesign Google Maps - Road Graph, Routing Algorithm, ETA ComputationUber - Driver Matching, Surge Pricing, Real-Time Location TrackingYelp / Proximity Service - Geohash, Quadtree, Nearby Search
23
Social Media and Feed Systems
6 patterns
Design a Generic Newsfeed System - Pull vs Push vs Hybrid Fan-Out at Any ScaleDesign Facebook News Feed - EdgeRank, Fan-Out on Write vs ReadInstagram - Photo Upload, Feed, Stories, ExploreDesign LinkedIn - Professional Graph, Feed, Job RecommendationsDesign Reddit - Voting, Ranking, Community Architecture at ScaleDesign Twitter - Tweets, Follow Graph, Timeline Generation at Scale
24
Search and Discovery
7 patterns
Design a Hotel Booking System - Inventory, Reservation, Double Booking PreventionDesign a Job Portal - Search, Candidate Matching, Application TrackingDesign a Typeahead Suggestion System - Trie at Scale, Ranking, Personalization, CacheDesign Airbnb - Search, Booking, Calendar Availability, Review SystemDesign an E-Learning Platform - Course, Video, Progress, Certificate at ScaleDesign Google Search - Crawling, Indexing, PageRank, Query ProcessingDesign Quora - Q&A Feed, Search, Ranking, Spam Detection, Follow Topics
25
Video and Media Streaming
5 patterns
Design a Live Streaming Platform - Low-Latency RTMP to HLS PipelineNetflix - Personalization, Adaptive Streaming, Global CDN ArchitectureSpotify - Audio Streaming, Playlist, Offline Download ArchitectureDesign TikTok - Short Video Upload, For-You Feed Algorithm, Creator StackDesign YouTube - Upload, Transcoding Pipeline, CDN Delivery, View Count
26
Communication and Messaging Systems
5 patterns
Design a Notification System - Push, SMS, Email Fan-Out at 10M+ ScaleDesign a Video Calling System - WebRTC, Signaling Server, Media ServerDesign Facebook Messenger - Group Chat, Presence, Message SyncDesign Slack - Workspaces, Channels, Real-Time Delivery at Scale, SearchDesign WhatsApp - Real-Time Chat, Delivery Receipts, End-to-End Encryption
27
Rate Limiting
6 patterns
Distributed Rate Limiting - Redis-Based Centralized Counter ApproachFixed Window vs Sliding Window Counter - Trade-offsLeaky Bucket Algorithm - Smoothing Traffic Bursts to Steady RateRate Limiting at Different Layers - API Gateway, Service, DatabaseToken Bucket Algorithm - Design, Implementation, and Burst HandlingWhy Rate Limiting Exists and What Happens to Systems Without It
28
Networking and Protocols
7 patterns
DNS Load Balancing and GeoDNS for Global Traffic DistributionForward Proxy vs Reverse Proxy - What Each Hides and Why It MattersHow DNS Works - Resolution Chain from Browser to IP AddressHTTP 1.1 vs HTTP 2 vs HTTP 3 - What Changed and Why It MattersHTTP vs HTTPS - TLS Handshake, Certificate Chain, and the CostTCP vs UDP - When Reliability Matters and When Speed WinsWebSockets vs Long Polling vs Server-Sent Events - When to Use Each
29
Databases - NoSQL
6 patterns
Document Databases - MongoDB Data Modeling Patterns at ScaleGraph Databases - When Relationships Are the Primary DataKey-Value Stores - Redis vs DynamoDB, Use Cases, Trade-offsTime-Series Databases - Metrics, Events, and IoT PatternsWhy NoSQL Exists and When SQL is the Wrong ToolWide-Column Stores - Cassandra Partitioning and Data Modeling
30
Search and Indexing
5 patterns
31
Load Balancers
6 patterns
Global Server Load Balancing - Routing Traffic Across Data CentersHealth Checks and Automatic Failover in Load BalancersLayer 4 vs Layer 7 Load Balancing - Transport vs Application LevelLoad Balancer vs API Gateway vs Reverse Proxy - Key DifferencesLoad Balancing Algorithms - Round Robin, Least Connections, IP Hash, WeightedWhy Load Balancers Exist and What Problems They Solve
32
Unique ID Generation
5 patterns
Why LeyaaNot just a course. A learning intelligence.
Leyaa doesn't just deliver content - it understands where you are, what you need, and how to get you there fastest.
Adaptive Diagnostics
Leyaa identifies which of the 186 patterns you've mastered and which need work - before you waste time on what you already know.
Pattern-Level Precision
Every pattern gets a verdict - Learn, Practice, or Skip - so your study time goes exactly where it counts.
Intelligent Pacing
Leyaa reads your velocity across the whole course and adapts your focus list dynamically, keeping you in the optimal learning zone.
Before & After Visibility
Every assessment creates a snapshot. Retake anytime to see exactly how much you've grown - pattern by pattern.
Learner Autonomy
Leyaa recommends, never restricts. Override any suggestion and explore at your own pace - the system tracks everything regardless.
Clear Learning Path
A structured journey through 32 topics, where each one sets you up perfectly for the next.
HLD
Ready to master HLD?
Start your journey today
Start your diagnostic now. Build mastery across all 186 patterns in under 15 minutes.
186 Patterns
Personalized roadmap
