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• Service Workers Explained: Offline-First Caching Without Stale AppsFrontend · A plain-English guide to service workers: caching strategies per file type, the install, waiting and activate lifecycle, and safe updates, shown on one running example of a delivery riders' drop-list app.21 min read · Updated 25 Oct 2026
• Session Replay Explained: How DOM Recording Masks Passwords and PIIFrontend · A plain-English guide to session replay: how it records DOM snapshots and changes instead of video, how masking keeps passwords and PII out, what consent requires and how big recordings get, shown on one running example of a store's checkout bug.19 min read · Updated 25 Oct 2026
• Splitwise System Design: LLD for Splits, Balances and Debt SimplificationSystem design · A plain-English guide to Splitwise system design at the class level: groups, expenses, three split rules in paise, net balances and greedy debt simplification, shown on one running example of four flatmates sharing bills.23 min read · Updated 25 Oct 2026
• Storybook's October 2026 Vulnerabilities Explained: Lock Down Your Dev ServerFrontend · A plain-English guide to the two October 2026 Storybook dev server advisories: how a website or a Wi-Fi neighbour could write story files, what the fixed versions change and how to check your setup, shown on one running example of a design-system repo.20 min read · Updated 25 Oct 2026
• Trending Topics System Design: Count-Min Sketch, Top-K and Time DecaySystem design · A plain-English guide to trending topics system design: Count-Min Sketch counting, top-k lists, time decay, per-city boards and keeping bots out, shown on one running example of a social app's trending box.25 min read · Updated 25 Oct 2026
• Agent Failure Recovery: Checkpoints and Partial FailuresAI and GenAI · A plain-English guide to agent failure recovery: how checkpoints, idempotency keys and undo steps let a crashed AI agent resume safely, shown on one running example of a nightly invoice check.25 min read · Updated 24 Oct 2026
• Design an AI Code Review Bot: PR Comments, Noise and CostAI and GenAI · A plain-English guide to AI code review system design: how a bot reads pull requests, cuts false positives and keeps cost per review low, shown on one running example of a review bot sold to software teams.25 min read · Updated 24 Oct 2026
• API Gateway vs BFF: One Shared Front Door or One Backend for Each AppBackend · A plain-English guide to API gateways and the backend-for-frontend pattern: what each layer does, how they differ and when you need both, shown on one running grocery app example.19 min read · Updated 24 Oct 2026
• Autoscaling Explained: Scale on the Right SignalBackend · A plain-English guide to autoscaling: how the scaling loop works, which metric to pick, how to beat spikes and stop flapping, shown on one running example of a flash-sale checkout.27 min read · Updated 24 Oct 2026
• The 2017 AWS S3 Outage Explained: One Typo, Four HoursSystem design · A plain-English guide to the 2017 AWS S3 outage: the mistyped command, why it spread, why recovery was slow and what AWS changed, shown on one running example of an online print shop.23 min read · Updated 24 Oct 2026
• Backpressure Explained: Slowing Producers Before Queues ExplodeSystem design · A plain-English guide to backpressure: why queues blow up when producers outrun consumers, and how bounded queues, pull, load shedding and 429s fix it, built on one running SMS gateway example.20 min read · Updated 24 Oct 2026
• Batch vs Stream Processing Explained: Late Data, Lambda and KappaSystem design · A plain-English guide to batch vs stream processing: daily jobs, live windows, late data and watermarks, and the Lambda and Kappa architectures, shown on one running example of a rooftop-solar monitoring service.25 min read · Updated 24 Oct 2026
• Blob Storage Design: How an S3-Style Store Keeps Files SafeSystem design · A plain-English guide to blob storage design: chunks, metadata, copies, erasure coding and repair, shown on one running example of a team storing 400 TB of customer files.25 min read · Updated 24 Oct 2026
• Calendar System Design: Recurring Events and Time ZonesSystem design · A plain-English guide to calendar system design: recurring events as rules, exceptions, time zones, daylight saving, reminders and week views, shown on one running example of a weekly family video call.24 min read · Updated 24 Oct 2026
• Cassandra Consistency Explained: Levels, Quorums and RepairSystem design · A plain-English guide to Cassandra consistency levels, how reads and writes wait for replicas, and how to pick a level per query, built on one running farm-sensor example.19 min read · Updated 24 Oct 2026
• Clock Synchronization Explained: Why Server Timestamps Lie and What to DoSystem design · A plain-English guide to clock synchronization: why server clocks drift, how NTP corrects them, why timestamps still lie, and what TrueTime does, built on one running cardamom auction example.26 min read · Updated 24 Oct 2026
• Design Google Docs: OT vs CRDTsSystem design · A plain-English guide to collaborative editing that compares operational transformation and CRDTs, shown on one running example of a small-team document editor.20 min read · Updated 24 Oct 2026
• Core Web Vitals Explained: LCP, INP and CLS With Real FixesFrontend · A plain-English guide to Core Web Vitals: what LCP, INP and CLS measure, the good lines, and the fixes that move each one, shown on one running example of an online jewellery store's product page.28 min read · Updated 24 Oct 2026
• CPU vs GPU vs TPU for AI: Which Chip for Which JobAI and GenAI · A plain-English guide to choosing between CPUs, GPUs and TPUs for training, inference and embeddings, shown on one running example of an Indian-language search team.26 min read · Updated 24 Oct 2026
• Disaster Recovery: RTO, RPO and Multi-Region PlanningBackend · A plain-English guide to disaster recovery, from RTO and RPO to backups, warm standby and region failover, built on one running pension-records example.26 min read · Updated 24 Oct 2026
• Event Sourcing and CDC: Store Events, Derive StateSystem design · A plain-English guide to event sourcing, change data capture and the outbox pattern, built on one running example of a prepaid society wallet in Ahmedabad.26 min read · Updated 24 Oct 2026
• The 2021 Facebook Outage Explained: BGP and DNSSystem design · A plain-English guide to the 2021 Facebook outage, from the backbone command and the BGP withdrawals to the DNS loss and the slow recovery, shown on one running example of a regional internet provider.19 min read · Updated 24 Oct 2026
• Fallacies of Distributed Computing: Crash, Omission, ByzantineSystem design · A plain-English guide to the eight fallacies of distributed computing and the failure models behind them, built on one running drone fleet example.20 min read · Updated 24 Oct 2026
• Design Dropbox or Google Drive: File Sync System DesignSystem design · A plain-English guide to file sync system design: chunking, uploads, change journals, conflicts and storage maths, shown on one running example of a shared office folder.26 min read · Updated 24 Oct 2026