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System Design Articles

Architecture deep dives, scaling trade-offs, reliability patterns, and system design walkthroughs for backend engineers.

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System Design

Idempotency Keys in APIs: Retries, Duplicate Requests, and Exactly-Once Illusions

Any API that changes state will eventually receive the same request more than once. Mobile clients retry on flaky networks. Load balancers retry after connection resets. Users double-click. Workers crash after doing the …

Apr 7, 2026·7 min read

#idempotency#api design#distributed systems

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System Design

Multi-Region Architecture: Active-Active, Active-Passive, and Consistency Trade-Offs

Multi-region architecture is expensive insurance. It can improve availability and latency, but it also makes data consistency, deployment, observability, and operations much harder. Before designing multi-region, ask two…

Apr 7, 20265 min read

#multi-region#system design#distributed systems

System Design

Production Incident Playbooks: Debugging Latency, Errors, and Traffic Spikes

Production incidents are not solved by heroics. They are solved by reducing uncertainty quickly. When latency jumps, errors spike, or a queue backlog grows, the worst thing a team can do is randomly restart services, add…

Apr 7, 20265 min read

#incident response#production debugging#observability

System Design

System Design: Building an Audit Log System for Compliance and Debugging

Audit logs answer a simple question: who did what, to which resource, from where, and when? That question matters during security investigations, customer support, compliance audits, data recovery, and debugging. A norma…

Apr 7, 20265 min read

#system design#audit logs#compliance

System Design

Transactional Outbox Pattern: Reliable Event Publishing Without Dual Writes

The transactional outbox pattern solves one of the most common reliability bugs in distributed systems: the dual-write problem. Imagine an order service that writes to PostgreSQL and publishes an event to Kafka: This lo…

Apr 7, 20268 min read

#transactional outbox#kafka#event driven architecture

System Design

Building Production Observability with OpenTelemetry and Grafana Stack

Observability is not the same as monitoring. Monitoring tells you something is wrong. Observability lets you understand why — by exploring system state through metrics, traces, and logs without needing to know in advance…

Jul 3, 20256 min read

#observability#opentelemetry#prometheus

System Design

Event Sourcing and CQRS in Production: Beyond the Theory

Event sourcing is one of those patterns that looks elegant in conference talks and becomes surprisingly complex in production systems. The theory — store events instead of state, derive state by replaying events — is sou…

Jun 23, 20257 min read

#event sourcing#cqrs#system design

System Design

gRPC vs REST vs GraphQL: Choosing the Right API Protocol

API protocol selection has a longer lifespan than almost any other technical decision. REST APIs from 2010 are still running in production. gRPC services chosen for internal communication in 2018 are tightly coupled to t…

Jun 18, 20257 min read

#grpc#rest#graphql

System Design

Multi-Tenancy Architecture: Database, Application, and Infrastructure Patterns

Multi-tenancy is the architecture pattern where a single deployed instance of a software system serves multiple customers (tenants), with each tenant's data logically or physically isolated from others. It's the foundati…

May 24, 20258 min read

#multi-tenancy#saas#system design

System Design

Designing a Retry System Without Causing a Retry Storm

Retry logic is the second most dangerous code in a distributed system, after "delete all records." The intent is to improve reliability by recovering from transient failures. The actual effect, when implemented naively, …

May 22, 202510 min read

#retry#circuit breaker#resilience

System Design

Feature Flags and Progressive Delivery: Safe Releases at Scale

Feature flags — also called feature toggles or feature switches — decouple code deployment from feature release. You deploy code to production with the new feature disabled. When you're ready, you enable it for 1% of use…

May 19, 20257 min read

#feature flags#progressive delivery#deployment

System Design

Microservices Are Overrated for Most Startups

The microservices hype peaked around 2016. In 2025, some of the most respected engineering teams in the industry are quietly talking about their microservices regret. Segment famously consolidated 130+ microservices back…

May 16, 20259 min read

#microservices#monolith#architecture

System Design

Designing a High-Throughput Notification System for 100K Events per Second

100,000 events per second is not a notification system problem — it's a data pipeline problem that happens to produce notifications. Teams that approach it as a features problem ("we just need push, email, and SMS") buil…

May 10, 202510 min read

#system design#notifications#kafka

System Design

WebSocket and SSE for Real-Time Systems: Architecture and Production Patterns

Real-time features — live notifications, collaborative editing, live dashboards, streaming data — require pushing data from server to client without the client repeatedly polling. HTTP polling wastes resources and adds l…

May 4, 20257 min read

#websocket#sse#real-time

System Design

Designing Idempotent Payment Systems in Distributed Architecture

Duplicate payments are not a theoretical edge case. In any distributed payment system operating at scale, they are a guaranteed occurrence. Networks time out. Clients retry. Proxies retry on behalf of clients. Load balan…

Apr 26, 202511 min read

#payments#idempotency#distributed systems

System Design

Service Mesh with Istio: mTLS, Traffic Management, and Observability

A service mesh solves three problems that grow exponentially with microservice count: security (every service-to-service call should be encrypted and authenticated), reliability (circuit breaking, retries, timeouts consi…

Mar 31, 202512 min read

#istio#service mesh#kubernetes

System Design

System Design: Video Streaming Platform at Netflix Scale

Netflix accounts for 15% of global internet traffic. At peak, it serves 250 million concurrent streams — each stream adapting in real-time to network conditions, each segment served from servers 20ms away from the viewer…

Mar 19, 202511 min read

#system design#video streaming#cdn

System Design

System Design: Real-Time Chat Application at Scale

Real-time chat systems are among the most architecturally interesting distributed systems. They require persistent connections at massive scale, exactly-once message delivery guarantees, presence detection across million…

Mar 17, 202511 min read

#system design#websocket#real-time

System Design

Distributed Tracing with OpenTelemetry: End-to-End Observability

A request enters your system, touches 8 services, and takes 3 seconds. Which service is slow? Without distributed tracing, you're correlating timestamps across 8 log files. With distributed tracing, you click on the trac…

Mar 5, 202511 min read

#observability#opentelemetry#distributed tracing

System Design

Event-Driven Architecture: CQRS and Event Sourcing in Practice

Traditional CRUD systems store current state. Event-driven systems store the history of state changes. This single difference is more profound than it first appears: instead of asking "what is the current status of order…

Mar 3, 202514 min read

#event sourcing#cqrs#event-driven

System Design

API Design: REST vs GraphQL vs gRPC — When to Use Each

Every microservices architecture makes an implicit bet on an API protocol. REST is familiar but verbose. GraphQL is flexible but complex. gRPC is fast but opinionated. Choosing wrong costs you months of refactoring. This…

Mar 1, 202513 min read

#api#rest#graphql

System Design

Microservices Patterns: Circuit Breaker, Retry, Bulkhead, and Saga

A monolith fails as a unit — one process, one crash, everything stops. A microservices system fails differently: some services go down, some slow to a crawl, some remain perfectly healthy. This partial-failure behaviour …

Feb 28, 202514 min read

#microservices#resilience#circuit breaker

System Design

System Design: Search Autocomplete at Google Scale

Search autocomplete — the dropdown that appears as you type — seems simple but is one of the most latency-sensitive features in any product. Google returns suggestions in under 100ms for billions of queries per day. This…

Feb 20, 202511 min read

#system design#search#autocomplete

System Design

System Design: Building a Notification System for 100 Million Users

Notification systems are deceptively complex. Sending one notification is trivial. Sending 100 million notifications daily — with channel routing, user preferences, delivery tracking, retry logic, and rate limiting — req…

Feb 18, 202511 min read

#system design#notifications#kafka

System Design

System Design: Building a URL Shortener That Handles Billions of Requests

The URL shortener is the "Hello World" of system design interviews — but most candidates treat it superficially. The interesting parts are not in generating a short code; they're in the numbers that reveal the true scale…

Jan 29, 202512 min read

#system design#distributed systems#databases

System Design

System Design: Distributed Rate Limiter — Token Bucket vs Sliding Window

Rate limiting is deceptively simple in concept and surprisingly tricky in distributed systems. Every API at scale — Stripe, GitHub, Twitter — implements rate limiting. Done wrong, it allows bursts that overwhelm backends…

Jan 8, 202510 min read

#system design#rate limiting#redis

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