Grokking ExpressJS
Build web servers and REST APIs with Express 5: middleware, routing, databases, JWT authentication, security, uploads, WebSockets, testing, and production.
Course Overview
Express is the most widely used web framework for Node.js. It takes the raw requests that Node.js receives, passes each one through a series of functions that you write, and helps you send a clear response. This course teaches you to build web servers and HTTP APIs with it, and to predict what Express does with every request your server receives. You start with a server that answers a single request, then learn middleware, routing by method and path, routers, and error handling in one place. Next you design a REST API, test it with Postman, and validate what clients send. The middle of the course connects the API to MongoDB with Mongoose and to PostgreSQL with Sequelize, then adds password hashing, JSON Web Tokens, Helmet, CORS, and rate limiting. Later chapters cover file uploads with Multer, HTML forms, and real-time features with WebSockets and Socket.IO. You then test routes with Jest and Supertest, debug with the Node.js inspector, and log with morgan and Winston. The last chapters run the app in production with PM2, Nginx, Redis caching, streams, and worker threads. Every example targets Express 5 and was run on Express 5.3 and Node.js 24, and every chapter ends with an assessment that explains each answer.
What you'll learn in Grokking ExpressJS
- Explain what Express adds to Node.js, and trace one request from the client to the response.
- Route requests by method and path with the Express 5 path syntax, and split routes into routers.
- Handle errors in one place, including errors thrown inside async route handlers.
- Store data in MongoDB with Mongoose and in PostgreSQL with Sequelize, and choose between SQL and NoSQL.
- Secure an API with Helmet, CORS, and rate limiting, and know what each one protects against.
- Build real-time features with WebSockets and Socket.IO, including rooms and broadcasts.
- Run an app in production with PM2, Nginx, Redis caching, streams, and worker threads.
- Write middleware that reads, changes, or answers a request, and put it in the right order with next().
- Choose between route and query parameters, and group and version an API under one prefix.
- Design a REST API with clear resources, status codes, and validation errors, and test it with Postman.
- Hash passwords with bcrypt, and protect routes with JSON Web Tokens and refresh tokens.
- Accept file uploads with Multer, check their real type and size, and read HTML form data.
- Test routes with Jest and Supertest, debug with the Node.js inspector, and log with morgan and Winston.
Course Content
File Uploads and Handling Forms
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About the Author
Arslan Ahmad
Industry Expertise & Leadership
Arslan Ahmad is the lead author of Grokking ExpressJS. As the founder of Design Gurus and a former FAANG hiring manager, he has worked at industry giants like Facebook (now Meta) and Microsoft.
He has conducted hundreds of system design interviews, giving him unique insight into what top tech companies look for in candidates.
The course also incorporates expertise from senior engineers at Google, Meta, Amazon, Microsoft, and Uber, ensuring you learn system design best practices from professionals who have built and scaled real-world systems.
500+
Interviews Conducted
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FAQs
What is Grokking ExpressJS?
It is a course on building web servers and HTTP APIs with Express, the most widely used web framework for Node.js. It starts with a server that answers one request, then covers middleware, routing, REST API design, databases, authentication and security, file uploads, real-time features, testing and debugging, and running an app in production.
Who is this course for?
It is for JavaScript developers who want to move into backend development, frontend developers who want to build the services their applications call, and backend developers who know another framework and want to learn how Express does the same work. It does not assume any earlier experience with a web framework.
What do I need to know before I start?
You should be able to write JavaScript, including objects, arrow functions, modules, and promises with async and await. You should also have used Node.js and npm before, because the course builds on them rather than teaching the runtime itself.
Which versions of Express and Node.js does the course use?
The course teaches Express 5 on a current Node.js LTS release, and every example was run on Express 5.3 and Node.js 24 during the review. Where Express 4 behaves differently, for example in route path syntax and in how errors from async functions are handled, the lesson says so, which helps when you work on an existing project.
What do I need to follow along?
You need a current Node.js LTS release, a terminal, and a code editor. The lessons send requests with curl or a browser, and the API chapter introduces Postman. The database lessons use MongoDB, which you can run locally or in MongoDB Atlas, and PostgreSQL. The course does not include a coding environment in the browser, so you run the examples on your own computer.
Does the course use JavaScript or TypeScript?
The examples are written in JavaScript and load packages with require(). The course does not teach TypeScript, so you can follow it with JavaScript alone.
How is this course different from Grokking Node.js?
Grokking Node.js teaches the runtime itself, including the event loop, modules, the file system, asynchronous code, and a web server written with the http module, and it introduces Express in one chapter. This course assumes those basics and builds every topic inside an Express app, with more depth on routers, API versioning, validation, error handling, uploads, and real-time features.
Does the course cover authentication and security?
Yes. You compare sessions, tokens, OAuth, and API keys, hash passwords with bcrypt, and protect routes with JSON Web Tokens and refresh tokens. You then add Helmet for security headers, CORS rules for browser clients, and rate limiting, with an explanation of what each one does and does not protect against.
Are there quizzes or assessments?
Yes. Every chapter ends with an assessment, and each attempt draws a set of questions from a larger pool, so a second attempt gives you different questions. Most questions describe a request or a piece of code and ask what Express does with it, and every option comes with an explanation.
What does the course not cover?
It does not teach TypeScript, GraphQL, frontend frameworks, or deployment to a specific cloud platform or container system. It covers running an app in production with PM2, Nginx, and Redis, which apply on any Linux server.
