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Backend from Scratch

A free course to learn backend development from scratch: what happens behind every website and app, from the wires of the internet to AI agents. It’s for anyone: you don’t need to know backend or how to code to start, because every concept is explained from the beginning, with examples you can try yourself.

Even if backend isn’t your goal

Section titled “Even if backend isn’t your goal”

The first phases explain how the web works under the hood: how data travels across the internet, how you run a server from the terminal, and how the browser and the server talk over HTTP. That’s useful to anyone who works with the web, not just people who write backend code.

  • If you do frontend, you’ll understand what happens after every fetch and why it sometimes fails.
  • If you design or work in product, you’ll know what your engineering team is talking about.
  • If you’re curious, you’ll know what really happens when you open a website.

Every lesson has something hands-on

Section titled “Every lesson has something hands-on”
  • Try it in your terminal: guided exercises with real tools like curl, dig or nc.
  • Playgrounds: real tools inside the site, like a database or cryptography, running in your browser.
  • Labs: step-by-step simulations for the hardest things to see: HTTP, DNS, TCP and Docker.

The playgrounds and labs published so far, all together, in playgrounds.

Roadmap

Section titled “Roadmap”

This course is written while it is being learned, and phases are published one at a time. The roadmap has the details.

  • phase-0How the internet works 9 of 9 lessons

    Client-server, protocols, network layers, IP, TCP, DNS and TLS: how data travels before you write a single line of backend code.

  • phase-1Terminal, Linux and SSH(Coming soon)

    Where almost every backend lives: the shell, permissions, processes, environment variables and how to log into a remote server.

  • phase-2HTTP in depth(Coming soon)

    The web's protocol from the side that answers: methods, status codes, headers, cookies, CORS and caching.

  • phase-3Your first server(Coming soon)

    Node.js and TypeScript: an HTTP server without a framework, then with one, input validation, errors, logs and the event loop.

  • phase-4API design(Coming soon)

    REST done right, OpenAPI, and when to use GraphQL, gRPC, WebSockets, Server-Sent Events or webhooks.

  • phase-5Databases(Coming soon)

    SQL with PostgreSQL, modeling, indexes, transactions, migrations, ORMs and when NoSQL makes sense.

  • phase-6Authentication, authorization and security(Coming soon)

    Passwords, sessions and JWT, OAuth and OpenID Connect, roles and permissions, and the OWASP Top 10.

  • phase-7Docker and containers(Coming soon)

    The end of “works on my machine”: images, containers, Dockerfiles, volumes, networks and Docker Compose.

  • phase-8Deployment and infrastructure(Coming soon)

    Your own server: VPS, reverse proxy, domain and HTTPS, CI/CD, cloud models and infrastructure as code.

  • phase-9Architecture and scaling(Coming soon)

    Queues and background jobs, caching, horizontal scaling, monoliths vs microservices and distributed systems.

  • phase-10Quality and observability(Coming soon)

    Unit, integration and end-to-end tests; logs, metrics and traces; health checks and incident management.

  • phase-11Backend for AI and agents(Coming soon)

    Model APIs from the server, streaming, tool use, MCP, semantic search with embeddings and RAG, and AI in production.

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