8 min read An idempotency key service ensures that retried API requests do not cause duplicate side effects — a critical requirement for […] Read article
9 min read A content reporting and abuse detection system allows users to flag harmful content — spam, harassment, hate speech, illegal material Read article
10 min read A content tagging system lets users and systems attach descriptive labels to content — blog posts, products, images, videos — Read article
9 min read Cache warming ensures a cache is pre-populated with frequently accessed data before users experience cache misses. Without warming, a fresh Read article
9 min read A data archival system moves aged, infrequently accessed data from hot storage (fast, expensive) to warm or cold tiers (slower, Read article
10 min read Multi-factor authentication (MFA) adds a second verification layer beyond passwords — protecting accounts even when passwords are compromised. The three Read article
9 min read A follower graph stores directed relationships between users — Alice follows Bob, but Bob may not follow Alice. It powers Read article
8 min read A trending topics system surfaces content gaining rapid engagement — the top hashtags on Twitter, trending searches on Google, or Read article
8 min read An order tracking system maintains the lifecycle of a purchase from placement through delivery, providing real-time status to customers and Read article
8 min read A user presence system tracks whether users are online, offline, or idle — powering the green dots in Slack, WhatsApp, Read article
9 min read A payment processing pipeline accepts customer payment details, communicates with a payment processor (Stripe, Braintree, Adyen), and reliably records the Read article
9 min read A shopping cart and checkout system manages the in-progress purchase state from item addition through payment completion. Core challenges: persisting Read article
9 min read An organization hierarchy system models nested teams, departments, and reporting relationships — essential in B2B SaaS, HR platforms, and enterprise Read article
9 min read A link preview service fetches URL metadata (title, description, image) to render rich embeds when users share links — familiar Read article
9 min read Email verification confirms a user controls the email address they registered with, blocking fake accounts, disposable addresses, and typo’d emails Read article
