⏱ 7 min read What Is an Access Control List System? An Access Control List (ACL) system determines whether a given subject is permitted […] Read article

⏱ 9 min read A webhook delivery system must guarantee that every event reaches its destination endpoint even when the endpoint is temporarily unavailable. Read article

⏱ 8 min read A scheduled task manager triggers recurring jobs on cron schedules reliably across distributed infrastructure. The core problems are: parsing cron Read article

⏱ 7 min read A priority queue service ensures that high-urgency work is processed before lower-urgency work even when the system is under load. Read article

⏱ 8 min read API throttling enforces usage limits to protect infrastructure from abuse, ensure fair resource allocation across tenants, and give customers predictable Read article

⏱ 7 min read Backpressure is the mechanism by which an overwhelmed consumer signals upstream producers to slow down. Without it, producers fill unbounded Read article

⏱ 7 min read Blue-green deployment eliminates downtime by maintaining two identical production environments. At any moment, one environment (blue) serves 100% of live Read article

⏱ 7 min read Dark Launch System Low-Level Design A dark launch (also called shadow testing or dark traffic) deploys a new service version Read article

⏱ 8 min read Saga Compensation Pattern Low-Level Design Distributed transactions across microservices cannot use two-phase commit at scale — it introduces tight coupling Read article

⏱ 7 min read Message Deduplication System Low-Level Design Distributed messaging systems face a fundamental challenge: networks are unreliable, and any message may be Read article

⏱ 7 min read Cache Invalidation System: Low-Level Design Cache invalidation is famously the hardest problem in computer science. A well-designed invalidation system must Read article

⏱ 7 min read CQRS Pattern: Low-Level Design CQRS (Command Query Responsibility Segregation) separates the write path — commands that mutate state — from Read article

⏱ 7 min read Feature Flag Service: Low-Level Design A feature flag service lets engineering teams ship code dark, run controlled rollouts, and flip Read article

⏱ 6 min read Webhook Gateway: Low-Level Design A webhook gateway decouples internal event producers from external consumers. It accepts domain events, routes them Read article

⏱ 6 min read Time-Series Aggregation System: Low-Level Design Storing raw metrics at full resolution is expensive at scale. A time-series aggregation system ingests Read article