ACID Isolation Locking Lab
Simulate a checkout race to see how ACID isolation, row locks, table locks, MVCC snapshots, range locks, and serializable retries keep database state correct.
Guides
Browse interactive technology guides for system design, distributed systems, networking, databases, caching, and infrastructure failure modes.
All Guides 96 guides
ACID Transactions Visualization
Step through the four ACID guarantees — Atomicity, Consistency, Isolation, Durability — with undo/redo logging, 2PL and MVCC isolation, isolation levels, and ARIES crash recovery.
API Pagination
Learn API pagination patterns. Compare offset, keyset, and cursor pagination query costs and learn how drift anomalies occur.
API Security Visualization
Explore a 13-step API security visualization covering TLS, OAuth2/OIDC, API gateways, rate limiting, WAF filtering, validation, tokenization, CORS, safe errors, and centralized audit trails.
API Testing Types and Strategies
Explore an 11-step API testing visualization that shows how smoke, functional, integration, regression, load, stress, security, penetration, fuzz, and resilience checks protect an API.
Auto-Scaling (HPA) Simulator
Simulate Kubernetes Horizontal Pod Autoscaler scaling pod replicas based on CPU utilization. Watch pods spin up and down as traffic changes, experiment with scaling thresholds
Auto-Scaling Component Runtime Simulator
Test Kubernetes HPA autoscaling as explicit runtime components with parent-owned input ports, child injection, routed connector messages, component state, element state, controls
B-Tree Indexing Enhanced Simulator
Test database B-Tree indexing as explicit runtime components with parent-owned input ports, child injection, routed connector messages, buffer pool caching, and query planning.
Bresenham's Line Algorithm
Understand Bresenham's Line Algorithm, a highly efficient rasterization technique that determines which grid points should be plotted to approximate a straight line.
Browser Rendering Pipeline Visualization
Walk through how a browser turns HTML, CSS, and JavaScript into pixels: navigation, parsing, CSSOM, style calculation, layout, paint, compositing, and presentation.
Cache Invalidation Strategies Simulator
Simulate different cache invalidation strategies side-by-side. Watch how write-through, write-behind, cache-aside, and TTL-based invalidation handle reads, writes
Canary Deployment Lifecycle Visualization
Walk through the Canary Deployment lifecycle with guided steps for blue-green, canary, traffic split, observation window, rollback.
Cascading Timeout & Latency Injection
Analyze cascading failure propagation across microservices when latency or errors are injected, and test mitigation strategies using circuit breakers and retry limits.
CDN Edge Caching Simulator
Simulate a CDN with multiple edge PoPs, an origin shield, and an origin server. Watch cache hits, misses, SWR revalidations
CDN System Request Lifecycle Visualization
Explore an 18-step CDN walkthrough covering Anycast and GeoDNS routing, cache keys, cacheability, request coalescing, validators, stale serving, failover, purge propagation
Chat System Message Lifecycle Visualization
Walk through a horizontally scaled chat system from initial load balancing and heartbeat keepalives through presence registry lookup, cross-gateway Pub/Sub, receipts, offline queueing
CI/CD Pipeline Lifecycle Visualization
Walk through the CI/CD Pipeline lifecycle with guided steps for build cache, test matrix, security gate, artifact, canary rollback.
Circuit Breaker Pattern Simulator
Simulate the Circuit Breaker pattern with count-based and time-based sliding windows, slow-call rate thresholds, fallback components, and per-component details. Watch requests flow, timeout
Cloud Storage System (Google Drive/Dropbox)
Understand how cloud storage systems like Google Drive and Dropbox sync files. Explore block-level chunking, content-based deduplication, delta sync, push notifications
Code Deployment System
Explore the end-to-end flow of a production-grade deployment system. Learn the mechanics of rolling updates, Blue-Green swaps, Canary routing, and automated rollbacks.
Collaborative Editor System Design
Learn how a real-time collaborative editor keeps multiple people on the same document without making typing feel slow.
Consistent Hashing Lifecycle Visualization
Walk through the Consistent Hashing lifecycle with guided steps for hash ring, clockwise, virtual nodes, remap, hotspot.
Consistent Hashing Ring & Virtual Nodes
Explore consistent hashing and virtual nodes visually. See how keys map to servers on a circular hash ring and observe request routing, server additions, and failovers.
Database Connection Pool Simulator
Simulate a database connection pool managing connections between application threads and a database. Watch connections get checked out, used, and returned. Experiment with pool sizing
Database Indexing (B-Tree) Visualization
Walk through how a B+ tree database index routes point lookups, supports range scans through leaf links, handles page splits, uses the buffer pool, and competes with sequential scans.
Database Replication WAL and Failover Visualization
Step through primary-standby database replication, WAL streaming, replica lag, synchronous commit, failover, split-brain risk, and recovery.
Database Sharding Lifecycle Visualization
Walk through the Database Sharding lifecycle with guided steps for hash sharding, range sharding, scatter-gather, hotspot, rebalance.
Distributed Message Queue (Kafka Deep-Dive)
Explore Kafka as a distributed commit log through a 14-step visualization covering producer batching, partition leaders, ISR, high watermark, consumer offsets, failover, recovery
Distributed Tracing Lifecycle Visualization
Walk through the Distributed Tracing lifecycle with guided steps for trace id, span id, context propagation, waterfall, sampling.
Distributed Unique ID Generator
Explore how a distributed unique ID generator packs timestamp, node identity, and sequence bits into one signed 64-bit integer.
DNS Resolution
Follow a DNS query from your browser through recursive resolvers, root servers, TLD servers, and authoritative nameservers. See caching, TTLs, and record types in action.
Feature Flag Rollout Simulator
Simulate feature flag rollout strategies. Watch how percentage-based rollouts, user targeting, and kill switches control which users see new features.
Food Delivery Fulfillment Lifecycle
Follow a food delivery order through checkout, restaurant acceptance, courier dispatch, pickup, live tracking, and customer notification.
Food Delivery Fulfillment Lifecycle
Walk through the lifecycle of a food delivery order from checkout through restaurant acceptance, courier offers, pickup, tracking, and final customer notification.
Garbage Collection Mark-Sweep-Compact Visualization
Step through managed-runtime garbage collection: allocation, GC roots, reachability, stop-the-world marking, sweeping, compaction, leaks, and recovery.
Generational Garbage Collection Pipeline
Understand generational garbage collection visually. Follow how JVM-style runtimes manage memory through Eden, Survivor spaces (S0/S1), and the Old Generation
gRPC over HTTP/2 Visual Walkthrough
Step through how a gRPC call moves from a local client method to Protobuf bytes, HTTP/2 frames, streams, trailers, deadlines, retries, and HPACK compression.
Health Checks and Kubernetes Probes Visualization
Step through Kubernetes startup, readiness, and liveness probes; Service endpoint routing; container restarts; CrashLoopBackOff; dependency drains; and recovery.
Hotel Reservation Concurrency
Understand concurrency control in a hotel reservation system. Learn how inventory check, pessimistic locking, optimistic locking, idempotent payments, ledger logging
How to Design a System Like Instagram
A 19-step interactive guide to six Instagram-scale outcomes: media uploads, feed generation, bounded cache recovery, Reels ranking, direct messaging, and live delivery.
How to Design Effective and Safe APIs
Learn how effective APIs use resource naming, versioning, token authentication, rate limiting, and idempotency keys to stay safe.
HTTP/2 Multiplexing Visualization
Walk through how HTTP/2 replaces HTTP/1.1 connection queues with binary frames, stream identifiers, multiplexing, flow control, and scoped stream errors.
Instagram Feed and Media Lifecycle Visualization
Walk through Instagram's feed and media lifecycle from upload to image processing, metadata commit, hybrid feed fan-out, Redis inbox reads, CDN media fill, cache stampede degradation
JWT Lifecycle
Learn the JSON Web Token lifecycle step by step, from login and signing to stateless API validation, token expiration, refresh tokens, logout, and revocation tradeoffs.
Kafka in Production Lifecycle Visualization
Walk through the Kafka in Production lifecycle with guided steps for partition leader, ISR, acks=all, consumer lag, leader election.
Kafka Partition Rebalancing Lifecycle Visualization
Walk through the Kafka Partition Rebalancing lifecycle with guided steps for group coordinator, partition assignment, rebalance, consumer lag, heartbeat.
Kafka Storage Internals
Explore Kafka storage internals: partition log segments, sparse offset indexes, binary search lookup, page cache behavior, and zero-copy transfer.
Key-Value Store Dynamo Lifecycle Visualization
Walk through a Dynamo-style distributed key-value store lifecycle: consistent hashing, quorum writes and reads, LSM storage, vector clocks, hinted handoff, gossip recovery
Kubernetes Autoscaling Under Load
Simulate Horizontal Pod Autoscaler (HPA) and Cluster Autoscaler (CA) behavior under traffic spikes. Experiment with metrics collection lag, pod cold start delays (image pull and app boot)
Leaderboard with Sorted Sets
See how Redis Sorted Sets power real-time leaderboards with O(log N) inserts and O(log N + M) range queries. Watch ZADD, ZRANK, ZRANGE, and ZINCRBY in action.
Load Balancer Algorithms
Visualize no balancing, round robin, weighted routing, least connections, response time, IP hash, health removal, slow start, and L4/L7 routing decisions.
Load Balancer Crash Simulator
Experiment with HA failover, stale DNS/client caches, backend health checks, fail-open routing, overload, latency, and recovery when a load balancer crashes.
Message Queue Patterns
Understand pub/sub, point-to-point, and streaming patterns using Redis. Watch producers, consumers, and message brokers handle async communication across fire-and-forget, at-most-once, and at-least-once stream delivery guarantees.
News Feed System Lifecycle Visualization
Walk through a scale-out news feed lifecycle from publishing and moderation to fan-out, timeline cache reads, hydration, ranking, and recovery.
Notification System Delivery Lifecycle Visualization
Walk through a scalable notification system from event intake and queue buffering through priority handling, preference checks, idempotency, provider dispatch, opt-out drops, retry backoff
OAuth 2.0 & OIDC Flow Visualization
Walk through OAuth 2.0 Authorization Code and OIDC flows: redirects, consent, authorization code, PKCE verification, token exchange, API calls, state, nonce, token theft, refresh
OAuth 2.0 Auth Code Flow with PKCE
Follow the step-by-step OAuth 2.0 Authorization Code Flow with PKCE. Learn how code verifiers and SHA-256 code challenges defend Single Page Applications (SPAs) against authorization code...
Object Storage PUT/GET Lifecycle Visualization
Walk through an S3-like object storage system from PUT validation and multipart upload through erasure coding, metadata manifest commit, GET reads, drive failure, self-healing rebuild
Pastebin System Design
Explore the system design of a Pastebin service. Follow the step-by-step walkthrough to see how Base62 Key Generation (KGS), S3 Object Storage, Relational Database Metadata indexing
Payment System (Stripe)
Explore a Stripe-style PaymentIntent lifecycle, visualizing idempotency, client secrets, authentication, authorization, capture, webhooks, ledger posting, and reconciliation.
Raft Consensus Protocol
Understand how distributed systems achieve consensus through leader election, log replication, and safety guarantees. See how nodes communicate, vote, and recover from failures.
Rate Limiting Algorithms
Explore token bucket, sliding window, and leaky bucket algorithms. Watch how rate limiters protect APIs by tracking and throttling request rates in real time.
Rate Limiting Simulator
Experiment with token bucket rate limiting by changing request rate, bucket capacity, refill rate, and scenarios such as normal traffic, bursts, overload, and recovery.
Reactive Architecture Builder
Build a typed software architecture, change realistic capacity settings, and watch overload, backpressure, and Kubernetes recovery propagate through the system.
Redis Architecture
A comprehensive deep-dive into Redis internals: caching strategies, data structures, single-threaded execution, pipelining, persistence (RDB & AOF), replication, failover
Redis Caching Patterns
Visualize cache-aside, read-through, write-through, and write-behind caching patterns. See how Redis sits between your application and database to accelerate reads.
Redis Cluster Failover Lifecycle Visualization
Walk through native Redis Cluster failover: cluster-bus PFAIL and FAIL reports, master authorization, config epochs, and MOVED recovery.
Redis Crash & Cache Stampede
Simulate what happens when Redis crashes: cache timeouts, database fallback, cache stampede pressure, rising latency, 5xx errors, and recovery after Redis restarts cold.
REST API Cheatsheet
Master REST API fundamentals interactively: learn the 6 REST principles, break down URL anatomy, explore HTTP methods, and simulate filtering and pagination.
REST API vs GraphQL Data Fetching
Compare REST API waterfall calls with GraphQL nested data resolution. Animate network roundtrips, AST parsing, and database query differences.
Ride-Sharing Service (Uber/Lyft)
Explore geospatial indexing (Geohash vs QuadTree), real-time driver coordinates streaming, surge pricing dynamic feedback loops, and transactional trip matching states.
Search Autocomplete (Typeahead) System
Understand the end-to-end architecture of a low-latency Search Autocomplete/Typeahead system. Explore SQL limits, debouncing, Trie data structures, MapReduce aggregations, range sharding
Secure Web API Access
Learn how secure web API access compares token-based authentication, HMAC signatures, tamper checks, and replay protection across 13-step modeled stages.
Session Management with Redis
Learn how Redis manages user sessions across distributed web servers. See session creation, retrieval, expiration, and how sticky sessions differ from shared session stores.
SLO / Error Budget Burn Rate Simulator
Simulate SLOs and error budgets to see how traffic, failures, burn rates, alert thresholds, and feature freezes affect reliability decisions.
SQL Injection Attack Path
Walk through the SQL Injection lifecycle with guided steps for string concatenation, parameterized query, WAF, input validation, least privilege.
SQL Query Executor: Volcano Iterator Model
Understand the pull-based Volcano iterator execution model in SQL engines. Walk through open(), next(), and close() interfaces, see pipeline breakers like Hash Join
Stock Exchange System Design
Explore LMAX Disruptor sequencing, pre-trade risk validations, FIFO Limit Order Book matching, UDP multicast publishers, and market circuit breakers.
Surviving a Redis Crash
Walk through a Redis crash from healthy reads to degraded fallback, DB protection, circuit breaking, L1 hot keys, replica failover, gradual warm-up, and cache-optional correctness.
TCP Congestion Control
Simulate TCP congestion control mechanisms. Watch packets flow and observe Slow Start, Congestion Avoidance, and Fast Retransmit phases. Experiment with packet loss, latency
TCP SYN Flood & Mitigation
Walk through the TCP SYN Flood lifecycle with guided steps for SYN, SYN-ACK, ACK, backlog, and SYN cookies.
The Ultimate API Learning Roadmap
Learn the API roadmap from HTTP basics to REST, GraphQL, gRPC, authentication, gateways, performance, and integration patterns.
TikTok Recommendation and Delivery System
Walk through a TikTok-style short-video platform from creator upload through encoder output, Object Storage arrival, item embeddings, Two-Tower ranking, CDN pre-fetching, viewer playback, and feedback recovery.
TLS 1.3 vs TLS 1.2 Handshake
Compare the TLS 1.3 and TLS 1.2 handshake processes side-by-side. Understand 1-RTT negotiation, encrypted post-ServerHello messages, and forward-secret keys.
TLS Certificate Chain of Trust
Understand how browsers cryptographically validate TLS/SSL certificate chains of trust step-by-step. Learn about Leaf, Intermediate, and Root certificates, signatures, public keys
TLS Handshake
Watch the complete TLS 1.3 handshake unfold step by step. See ClientHello, ServerHello, key exchange, certificate verification, and how encrypted communication is established.
Tunable DB Consistency Simulator
Simulate tunable read/write consistency levels (One, Quorum, All) in a Dynamo-style replicated database ring. Slice network connections to create partitions, execute operations
URL Shortener System Design
Walk through a URL shortener from long URL submission and Base62 code generation through collision checks, sharded storage, redirect resolution, browser and Redis caching, shard failure
Web Crawler System Lifecycle Visualization
Walk through a distributed web crawler lifecycle from seed URLs to URL frontier scheduling, robots.txt policy, DNS resolution, fetching, parsing, Bloom filter dedupe, spider trap handling
WebRTC Video Conferencing (Zoom)
Understand the architectural components of video conferencing systems like Zoom. Follow call signaling, STUN/TURN network traversal, Mesh vs. SFU vs. MCU topologies
WebSocket Lifecycle & Frame Protocol
Explore the complete lifecycle of a WebSocket connection, from the HTTP 101 upgrade handshake to RFC 6455 frame format, XOR masking calculations, heartbeats, fragmentation, and teardown.
What Does an API Gateway Do?
Explore a 12-step API Gateway visualization covering TLS termination, request validation, firewall rules, JWT validation, rate limiting, service discovery, protocol translation, routing
What is GraphQL?
Explore the origins, architecture, and core benefits of GraphQL. See how it solves REST's over-fetching and under-fetching problems.
Yelp (Proximity / Location-Based Service)
Learn how proximity and location-based services like Yelp scale. Visualize geospatial database queries, geohashing, QuadTree partitioning, 8-neighbor proximity searches, geospatial caching
YouTube Video Streaming Lifecycle Visualization
Walk through a YouTube-style video streaming lifecycle from chunked upload to transcoding, HLS/DASH manifests, CDN edge fills, ABR playback, Kafka view events, batch counters
Zero-Copy Network I/O System Calls
Explore modeled read/write context switches and CPU payload copies, then see how supported sendfile transfers use page references, descriptors, and scatter-gather DMA.