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Designing a System to Detect and Respond to Coordinated Disinformation Campaigns A production-grade architecture for spotting coordinated inauthentic behavior across multiple accounts and platforms in real time — built for the chaos of a fast-moving breaking news event. 01 · Introduction02 · Problem03 · Architecture04 · Internals05 · Advanced06 ·…
Designing a System to Detect and Respond to Coordinated Disinformation Campaigns A production-grade architecture for spotting coordinated inauthentic behavior across multiple accounts and platforms in real time — built for the chaos of a fast-moving breaking news event. 01 · Introduction02 · Problem03 · Architecture04 · Internals05 · Advanced06 ·…
Designing a Real-Time Content Moderation Pipeline for Text, Images and Video Every second, someone somewhere is uploading a post, a photo, or a video that should never reach another human’s screen. How do platforms like Facebook, YouTube, and TikTok inspect that content, decide whether it’s safe, and act on it…
Solving the Cold-Start Problem in Recommendation Systems How do you recommend the right content to someone the system has never seen before? This is a complete, from-scratch walkthrough of designing a production-grade cold-start recommendation architecture — covering the algorithms, the services, the databases, the failure modes, and the exact questions…
Designing the Algorithmic Explore Page A ground-up, production-grade blueprint for a discovery feed that surfaces content from accounts a user has never followed — covering candidate generation, ranking, embeddings, feature stores, caching, and the trade-offs real platforms make at massive scale. 01 · Introduction02 · Problem03 · Concepts04 · Architecture05…
Designing a “Close Friends” Selective Content Sharing System A complete, production-grade walkthrough of how to build a social platform feature that lets a user post content visible only to a hand-picked subset of their followers — covering the data model, fan-out strategy, access control, caching, and the scaling decisions that…
A production-grade system-design walkthrough for a real-time checkout cross-sell & upsell recommendation engine at ~1M requests/minute: two-speed architecture (fast cache-driven online path + async Kafka/Flink/warehouse/model-registry offline path), Recommendation Orchestrator with a hard 40 ms timeout budget and static fallback, three-layer caching (edge, in-proc LRU, Redis cluster), Rules Engine as final…
Designing a System to Catch a Price Gone Wrong Before It Goes Viral A complete, from-scratch architecture for detecting anomalously low product prices — whether a fat-fingered seller mistake or a deliberate pricing attack — before an army of bargain hunters can place ten thousand orders on a $4,999 television…
A production-grade system-design walkthrough for subscription-box e-commerce: staggered recurring billing with idempotency keys, dunning with exponential backoff, preference-driven curation as constraint satisfaction, atomic optimistic inventory reservation, event-driven saga (billing → curation → fulfilment) over per-subscriber Kafka partitions, cutoff-aware APIs, PCI tokenisation at the gateway boundary, three-way reconciliation, and shadow →…
Designing a real-time credit approval system for Buy-Now-Pay-Later (BNPL) A deep, from-first-principles walkthrough of how to design a BNPL platform that decides — in a few hundred milliseconds — whether to approve a shopper’s installment plan at the checkout of a partner e-commerce site, at a scale of millions of…