9 min read Webhook Subscription System: Low-Level Design A webhook subscription system lets external developers register URLs to receive event notifications. Unlike the […] Read article
9 min read Payment Refund System: Low-Level Design A payment refund system reverses a completed charge — partially or fully — and ensures Read article
8 min read Activity Feed Aggregator: Low-Level Design An activity feed aggregator collects events from multiple services — post created, user followed, payment Read article
8 min read Document Versioning System: Low-Level Design A document versioning system preserves every historical state of a document so users can view, Read article
8 min read Invite System Low-Level Design An invite system lets existing users bring new members into a product — a workspace, a Read article
8 min read Email Unsubscribe System: Low-Level Design An email unsubscribe system lets users opt out of specific email categories while maintaining compliance Read article
9 min read Search Index System: Low-Level Design A search index system converts raw documents into a structure that supports fast full-text queries. Read article
10 min read Job Queue System: Low-Level Design A job queue system schedules and executes background work: sending emails, resizing images, generating reports, Read article
11 min read Approval Workflow System: Low-Level Design An approval workflow routes a request — a purchase order, a content post, a contract, Read article
8 min read Messaging Queue System: Low-Level Design A messaging queue decouples producers from consumers: producers publish messages without knowing who will process Read article
10 min read User Onboarding System: Low-Level Design A user onboarding system guides new users through the steps required to activate their account Read article
10 min read Read Replica Routing System: Low-Level Design A read replica routing system transparently routes read queries to replica databases while sending Read article
8 min read Distributed Counter System: Low-Level Design A distributed counter tracks a numeric value that many servers increment or decrement concurrently — Read article
9 min read CDN Cache System: Low-Level Design A CDN cache sits between origin servers and end users, serving cached copies of static Read article
10 min read Database Migration System: Low-Level Design A database migration system tracks schema changes as versioned, ordered scripts and applies them to Read article
