The Architect's Mindset

Choosing Your System's Structure: Monolith vs. Modular Monolith vs. Microservices vs. Serverless

The architecture that got you to 100 users will kill you at 100,000

Organizing Your Codebase: Monorepo vs. Polyrepo

It's not just a folder structure — it's a team coordination decision

How Services Talk to Each Other: Event-Driven vs. Request-Driven Architecture

Why your services shouldn't talk to each other directly

Splitting Reads from Writes: An Introduction to CQRS

Read and write patterns are different problems. Stop solving them the same way

Storing Every Change as an Event: Event Sourcing Explained

What if you never deleted anything and could replay history?

Data Isolation Models: Shared DB → DB-per-Tenant

One database for all customers or one per customer? The trade-off no one warns you about

Tenant Identification Strategies

Subdomains, paths, headers — how your app knows who's knocking

Tenant Configuration & Feature Inheritance

Global → Plan → Tenant → User. The hierarchy that runs every SaaS

Noisy Neighbor Problem & Mitigation

One bad tenant can bring down your whole platform

White-Labeling Architecture

When a customer wants it to look like their product, not yours

RBAC vs. ABAC vs. ReBAC vs. PBAC

Roles are not enough. Here's when they break down

Permission Granularity: Coarse → Row-Level

"Can access Billing" vs. "Can edit invoice #4821 in their region"

Sessions vs. JWTs; Token Storage; Refresh Strategies

Where you store your JWT is a security decision, not a preference

SSO / SAML / OIDC; MFA; API Auth Patterns

Every enterprise deal will ask: do you support SSO?

Session Management: Concurrency, Revocation, Device Binding

How do you log someone out of every device instantly?

REST vs. GraphQL vs. gRPC vs. WebSocket vs. SSE

Picking an API protocol isn't a tech choice. It's a product decision

API Versioning; Pagination (Offset vs. Cursor)

Offset pagination breaks at page 500. Here's what you use instead

Rate Limiting: Fixed, Sliding, Token Bucket, Leaky Bucket

Rate limiting is not about blocking users. It's about protecting your system

Idempotency, Retry Safety, Exponential Backoff

What happens when the payment request fires twice?

API Gateway; BFF Pattern

Should your mobile app and web app talk to the same API?

DB Selection: Relational vs. Document vs. Wide-Column vs. Graph vs. NewSQL

PostgreSQL isn't always the answer. But it usually is

Normalization vs. Denormalization vs. Hybrid

Normalized for writes. Denormalized for reads. Why not both?

Consistency Models: Strong, Read-After-Write, Eventual, Causal

You updated your profile. Why does the page still show the old name?

Caching: L1/L2/L3; Eviction Strategies

The cache that saved the database. And the one that corrupted production

Search Architecture; Blob Storage; Sharding & Partitioning

LIKE queries will betray you. Here's when to move to real search

SPA vs. SSR vs. SSG vs. ISR vs. Streaming SSR vs. Islands

Rendering strategy is not a framework decision. It's a product decision

State Management: React Query vs. Zustand vs. Redux vs. Context vs. URL

Most global state shouldn't exist. Here's what to use instead

Component Architecture: Design Systems, Styling Approaches

Build your own design system or adopt one? The honest answer

Bundling: Vite vs. Webpack; Code Splitting; Tree Shaking

Your bundle is 4MB. Your users on 4G are not happy

Forms, Validation, Optimistic vs. Pessimistic Updates

Optimistic UI feels fast. Until it has to roll back in front of the user

Service Communication: Sync vs. Async; Saga Pattern

Distributed transactions without distributed chaos

Resilience: Circuit Breaker, Bulkhead, Retry Policies

Your third-party API just went down. Does your whole system go with it?

Background Jobs: Queues, Cron, Workflow Engines

Some things shouldn't happen in the request cycle

Distributed Locking & Coordination

Two servers. One job. What could go wrong?

Config Management, Feature Flags, Secrets Management

Feature flags are not just for A/B tests. They're your kill switch

ETL vs. ELT vs. Streaming vs. Hybrid Pipelines

Batch is simple. Streaming is real-time. Hybrid is reality

Analytics DB: OLAP, ClickHouse, DuckDB; Data Modeling

Your production DB is not your analytics DB. Stop treating it like one

Product Analytics: Build vs. Buy; Event Taxonomy

The naming convention you skip today will haunt your data team for years

AI Integration: API vs. Self-Hosted; Prompt Management; Fallbacks

What happens to your AI feature when OpenAI has an outage?

RAG Architecture: Vector Stores, Chunking, Hybrid Search, AI Safety

Not all AI features need GPT-4. And not all search needs to be semantic

Cloud Strategy: Single vs. Multi vs. Hybrid

Multi-cloud sounds smart. Until you have to operate it

Compute: K8s vs. Managed Containers vs. PaaS vs. Serverless

Kubernetes is not a goal. It's a trade-off

Infrastructure as Code: Terraform vs. Pulumi vs. CDK

If your infra isn't in code, it's in someone's memory. That person will leave

Deployment Strategies: Rolling, Blue-Green, Canary, GitOps

How do you release at 3pm on a Friday and sleep at night?

CI/CD Pipelines; Branching; DB Migrations; Artifact Promotion

Build once. Promote everywhere. Never rebuild per environment

Application Security: XSS, CSRF, SAST/DAST, Supply Chain

The vulnerability wasn't in your code. It was in your dependency

Data Security: Encryption, Key Management, PII, Data Classification

Encryption at rest is table stakes. Here's what most teams miss

Observability: Logs, Metrics, Traces, Profiling; SLOs & Alerting

You can't fix what you can't see. Alert on symptoms, not causes

Testing Strategy: Pyramid, Contract Tests, Load Testing, Test Data

Unit tests tell you the code works. Load tests tell you it survives reality

Scaling Dimensions; Bottleneck Identification; FinOps; DR & HA

Scale is not just adding more servers. It's knowing which bottleneck to fix first