The @app.route Decorator
Bind a URL path to a view function.
The @app.route Decorator is a free Flask Academy lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Flask Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What a Route Is
A route connects a URL path to a Python function. When someone visits that path, Flask runs your function and sends back whatever it returns.
Meet the Decorator
You attach a route using @app.route, a decorator written on the line just above your function. It tells Flask which path this function should handle.
@app.route("/")
def home():
return "Welcome!"View Functions
The function below a route is called a view function. Its job is simple: build a response for one specific URL and return it.
The Path Argument
The string you pass, like "/about", is the URL path. It always starts with a slash and tells Flask exactly where this page lives.
@app.route("/about")
def about():
return "About us"The Root Path
A single slash, "/", is the root path. It is your home page, the page people see when they open your site with no extra path.
Returning a Response
Whatever your view function returns becomes the page body. A plain string is the simplest response Flask can send to a browser.
@app.route("/hi")
def hi():
return "Hi there"Why a Decorator?
The @ symbol means decorator. It registers your function with Flask without you calling anything by hand, so Flask knows about the route at startup.
Function Names Are Yours
The function name does not have to match the URL. Pick clear names like contact or profile, since Flask uses them later to build links.
One Decorator, One Path
Each @app.route binds one path to one function. Want another page? Write another decorator and another function below it.
@app.route("/contact")
def contact():
return "Email us"Order Inside the File
You can declare routes in any order in your file. Flask matches by the requested path, not by which function you wrote first.
Paths Are Case Sensitive
Route paths are case sensitive after the host. "/About" and "/about" are different URLs, so keep your paths lowercase and consistent.
Quick Check
Let us make sure the decorator clicked.
Recap
You now wire pages with @app.route: a path string, a view function, and a returned response. That trio is the heart of every Flask app. 🎉
Frequently asked questions
Is the “The @app.route Decorator” lesson free?
Yes — the full text of “The @app.route Decorator” is free to read here on the web, and the Flask Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Flask Academy course, upgrade to CoddyKit PRO.
What will I learn in “The @app.route Decorator”?
Bind a URL path to a view function. You practise Flask Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Flask Academy?
No prior experience is required. Flask Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “The @app.route Decorator” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Flask Academy lesson?
Yes. Every Flask Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- The @app.route Decorator
- How a Request Becomes a Response
- Return Strings, HTML, and Status Codes
- Multiple Routes in One App