Local to Production: Scaling Systems
How a small app on your laptop turns into a system serving millions of people — servers, databases, caching, the cloud, microservices and background jobs, explained from absolute zero with the math behind every decision and a clear rule for exactly when to add each piece.
Written byRohan Sharma
Local to Live
4 lessons- 10 min read
What happens when you run your code
Processes, ports and localhost: the three ideas underneath every "it runs on my machine" moment.
- 9 min read
What is a server, really
Why "server" is a role any machine can play, and what changes when you actually put one on the internet.
- 11 min read
The journey of a request
Following one HTTP request from a browser tab all the way to your server and back, hop by hop.
- 10 min read
What breaks first under real traffic
The four resources every server has a limited supply of, and how to tell which one is actually failing.
Local to Live Quiz
8 questions
The Database Problem
4 lessons- 10 min read
Direct database calls, and why they work at first
What a database connection actually costs, and why calling it straight from your app is the right first design, not a mistake.
- 11 min read
Slow queries and why indexes matter
The math of scanning a table row by row versus jumping straight to the answer, and how indexes make that jump possible.
- 10 min read
Read replicas and splitting reads from writes
What to do once queries are fast and connections are pooled, but the single database machine still can't keep up with read volume.
- 9 min read
Vertical vs horizontal scaling
The two fundamental directions any system can scale in, what each one actually costs, and why nearly every real system eventually needs both.
The Database Problem Quiz
10 questions
Scaling the App Layer
4 lessons- 9 min read
Statelessness and why it matters
The one design property that decides whether you can ever run more than one copy of your app server.
- 10 min read
Load balancers
The traffic cop in front of your fleet of app servers, how it picks who gets each request, and how it knows a server is unhealthy.
- 9 min read
Auto-scaling and when to actually add servers
How systems add and remove capacity automatically based on real load, and the concrete metrics and thresholds that trigger it.
- 9 min read
Horizontal scaling in practice
How stateless servers, load balancers and auto-scaling fit together into one working fleet, with containers as the practical delivery mechanism.
Scaling the Application Layer Quiz
10 questions
Caching for Speed
4 lessons- 10 min read
What caching actually is
Trading a little staleness for a lot of speed, and the memory hierarchy idea underneath every cache in a computer system.
- 10 min read
Cache invalidation and the standard caching patterns
The genuinely hard problem in caching: knowing when a cached answer has gone stale, and the standard patterns for handling it.
- 9 min read
Redis and in-memory data stores
The technology most caches are actually built on, what makes it so fast, and the other jobs it ends up doing beyond caching.
- 9 min read
CDNs and caching close to the user
Caching applied to physical distance itself — why a static file should be served from near the user, not from your one origin server.
Caching for Speed Quiz
10 questions
Async Work & Scheduling
4 lessons- 9 min read
Why not everything belongs in the request
The difference between work a user needs an answer to right now and work that can happen after the response is already sent.
- 10 min read
Message queues and background workers
The mechanism that reliably runs deferred work outside the request, and why it also protects services from traffic spikes.
- 8 min read
Scheduled jobs and cron
Work that isn't triggered by any request at all, but needs to run automatically on a timer, and how to do it safely across multiple servers.
- 8 min read
Putting the async pieces together
How synchronous requests, queues, workers and scheduled jobs combine into real multi-step background pipelines.
Async Work & Scheduling Quiz
10 questions
The Cloud
5 lessons- 9 min read
What cloud computing actually is
Renting someone else's computers by the minute instead of owning your own, and why that changes what's economically possible.
- 9 min read
When to actually move to the cloud
Self-hosting vs cloud isn't a binary religion — a concrete, numbers-based way to decide, and why the answer changes with scale.
- 9 min read
Elasticity, regions, and managed services
What the cloud actually enables beyond just renting a VM — scaling on demand, serving users worldwide, and offloading operations.
- 9 min read
Serverless and Functions-as-a-Service
What "serverless" actually means (there's still a server), how it bills you, and exactly when it's a good fit versus a bad one.
- 8 min read
Cloud-native building blocks in practice
A concrete tour of what a small team's real cloud setup looks like, and how every earlier module's concept maps onto real services.
The Cloud Quiz
13 questions
Microservices
4 lessons- 10 min read
The monolith, and why it wins by default
What a monolith actually is, why it's the right starting architecture for nearly every project, and where it genuinely starts to strain.
- 10 min read
What microservices actually cost
The real, honest tradeoffs of splitting a system into services — network calls, distributed transactions, and operational overhead.
- 9 min read
Where to draw service boundaries
How to actually decide what becomes its own service, using business domains and independent scaling needs as the guide.
- 9 min read
Holding it together in production
How independent services actually find and talk to each other reliably at runtime, and the patterns that keep one failing service from taking down the rest.
Microservices Quiz
10 questions
Putting It All Together
4 lessons- 12 min read
The scaling journey of one app, start to finish
One imaginary app followed from zero users to millions, with every tool from this course introduced at the exact moment it actually became necessary.
- 9 min read
A decision framework for scaling
A reusable, step-by-step framework for deciding what to add next, applicable to any real system rather than just the previous lesson's example.
- 12 min read
Production essentials you cannot skip: logging, monitoring, payments and cost
The practical, easy-to-overlook pieces every real production system needs — observability, error tracking, analytics, payments, and when to stop using free tiers.
- 10 min read
The ultimate scaling cheat sheet
Every trigger, tool, and formula from this course condensed onto one page for fast reference when a real decision is in front of you.
Putting It All Together Quiz
14 questions
Assessments
9 quizzesLocal to Live Quiz
Local to Live · 8 questions
The Database Problem Quiz
The Database Problem · 10 questions
Scaling the Application Layer Quiz
Scaling the App Layer · 10 questions
Caching for Speed Quiz
Caching for Speed · 10 questions
Async Work & Scheduling Quiz
Async Work & Scheduling · 10 questions
The Cloud Quiz
The Cloud · 13 questions
Microservices Quiz
Microservices · 10 questions
Putting It All Together Quiz
Putting It All Together · 14 questions
Local to Production: Scaling Systems Final Assessment
Final assessment · 17 questions