LEVEL 7 · BACKEND ENGINEERING

Course Core

Backend engineering

How backends work, framework-free: HTTP in depth, typed Node.js, the BookStore API in TypeScript with PostgreSQL and authentication, layered API design, testing strategies, and the building blocks every backend needs: caches, queues and file storage.

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When you finish, you can

  • Read and write raw HTTP and explain every part of a request and response
  • Build a typed HTTP API with controllers, services, repositories and DTOs
  • Store data in PostgreSQL with parameterized SQL
  • Test a backend at the unit, integration and end-to-end level
  • Explain when to add a cache, a queue or object storage, and what each costs

You build: The BookStore API: a TypeScript backend with PostgreSQL, authentication and tests, built without a framework

MODULE 1

HTTP and REST

  1. 1HTTP in depthSee the exact bytes of an HTTP request and response, then learn the parts every backend developer uses daily: headers, cookies, content types, methods and status codes.40 min
  2. 2Designing a REST APITurn the Task API into a well-designed REST API: resources and URLs, a written contract, filtering, sorting, offset and cursor pagination, versioning and one consistent error format.40 min

MODULE 2

Databases and SQL

  1. 3How databases workWhy a backend keeps its data in a database, how relational databases organise it into tables and relationships, and what keys, constraints, indexes, transactions and migrations do, with real PostgreSQL running inside Node.js.45 min
  2. 4SQL with PostgreSQLInstall PostgreSQL with an installer or with Docker, talk to it with psql, and learn the SQL every backend uses: create, insert, select, update and delete, with filters, sorting and paging, and parameterized queries that stop SQL injection.45 min
  3. 5Joins, grouping and transactionsCombine tables with joins, summarise data with group by and aggregates, filter groups with having, nest queries, control transactions yourself, measure queries with explain analyze, and connect Node.js to a real PostgreSQL server.45 min

MODULE 3

Testing

  1. 6Testing fundamentalsWhy automated tests matter, the difference between unit, integration and end-to-end tests, and how to write them with node:assert and Node's built-in test runner, including mocks, spies, isolated tests and a fresh test database. Then the same tests in Vitest.45 min

MODULE 4

TypeScript on the server

  1. 7"BookStore API: HTTP and routing"Start a TypeScript backend with no framework at all. Set up the folder, read configuration from the environment, write a small typed router, JSON helpers and error responses, and serve books and authors over HTTP.45 min
  2. 8"BookStore API: validation and PostgreSQL"Check every request body by hand with type guards, move the BookStore data into PostgreSQL with PGlite, write repositories with parameterized SQL, and map typed errors to 400, 404 and 409.50 min
  3. 9"BookStore API: authentication and tests"Add users to the BookStore. Hash passwords with scrypt, issue signed log-in tokens with a secret from the environment, protect the order routes, test it all with node:test, and then look honestly at what this hand-built backend now gets wrong.50 min

Course checkpoint

Prove you can move on. The checkpoint picks 20 questions at random from every lesson in this course. Get 16 right to pass. Your result is saved in this browser only.