Free courses in the order a MERN stack developer needs them: HTML, CSS and JavaScript for the page, React for the interface, then Node.js and Express for the server, MongoDB for the data and logins to keep it safe. One language, JavaScript, from the first tag to the last API route, and every lesson runs in your browser.
711,880+ codders enrolled across these courses
718 lessons808 challenges3,295 quiz questions
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A path certificate at the end, plus 16 along the wayEach step is a section of an existing Coddy course. Take them in order, or jump to the one you are missing: your progress is saved per course either way.
Write real code, query databases, build websites, and master AI prompts. Our interactive lessons cover every skill modern developers need.
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Double or Nothing
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Promotion zoneRead, listen, test yourself, ask the AI, or look up anything you've already covered. Every lesson meets you where you are.
A variable is a named container that stores a value you can reference later in your program.
In Python, you create one by writing the name, an equals sign, then the value you want to store.
The value can change over time. Reassigning the name simply points it to a new value.
Earn certificates for every course you complete. Add them to your LinkedIn profile and resume to showcase your coding expertise to employers.
Certificate of Completion
Python Fundamentals
Add to LinkedInA way to build a whole web application in JavaScript with four tools: MongoDB stores the data as documents, Express turns a Node.js program into a web server and API, React builds the interface that runs in the browser, and Node.js runs JavaScript on the server. The browser's React code calls the Express API, which reads and writes MongoDB.
MERN stands for MongoDB, Express, React and Node.js. The order is the letters of the word, not the order you learn them in: on this path you start with the page (HTML, CSS, JavaScript and React) and then move to the server (Node.js and Express) and the database (MongoDB).
Builds features from the database to the screen: designs the MongoDB documents, writes the Express routes that create, read, update and delete them, protects those routes with logins, and builds the React pages that call them. Because all four tools are JavaScript, one developer can follow a feature through every layer.
Yes. React and Node.js are two of the most used tools in web development, and Express and MongoDB are their most common partners, so the skills carry over even to teams that use a different database or framework. Learning one stack end to end also teaches how any web application fits together, which is what interviews test.
MERN for most people starting now. The two stacks share MongoDB, Express and Node.js and differ only in the front end: React in MERN, Angular in MEAN. React is the more widely used of the two and the easier one to start with, and moving to Angular later means learning one new framework, not a new stack.
Around eight to ten months at an hour a day to finish this path. HTML and CSS take about six weeks, JavaScript and the browser two to three months, React about a month, and the five Node.js sections (Node.js, Express, REST APIs, MongoDB, logins) another three months. If you already know JavaScript, start at the React step and it takes about four months.
Yes, on this path. Every lesson runs in the browser: React renders beside the editor, your Node.js programs run in a terminal and your servers answer a request bar, and the MongoDB section uses an in-memory database that speaks the MongoDB driver's API. When you build your own app later, you install Node.js and MongoDB on your computer and the code carries over.
Yes. Finish every step and you get one free certificate for the whole MERN Stack Developer path. It lists each course you finished on the way, and links each course's own certificate, so anyone can check every skill it names. You can add it to your LinkedIn profile. It is a certificate of completion from Coddy, not an accredited qualification.
