This content originally appeared on DEV Community and was authored by tarun
Have you ever wanted to build your own web application but didn’t know where to start? Flask, a lightweight and easy-to-use Python web framework, is the perfect choice for beginners and experienced developers alike. Whether you want to create a personal blog, a portfolio site, or even a data-driven web app, Flask has got you covered. In this guide, we’ll walk you through the entire process of building a simple yet functional web application using Flask.
What is Flask?
Flask is a micro web framework written in Python. Unlike Django, which comes with many built-in features, Flask is minimalistic and gives you full control over your application. Here are some key advantages of using Flask:
- Lightweight & Flexible: You only add the components you need.
- Easy to Learn: Simple syntax and minimal boilerplate.
- Scalable: Suitable for small projects and large applications.
- Extensible: Easily integrates with databases, APIs, and other tools.
Prerequisites
Before we dive into coding, make sure you have the following installed:
- Python (Version 3.x recommended)
- Flask Framework – Install using pip install flask
- A Code Editor – VS Code, PyCharm, or any text editor of your choice
- Basic Knowledge of Python
How to Build a Flask Python Web Application?
Step 1: Setting Up Your Flask Project
1.1 Create a New Project Directory
First, create a new folder for your Flask project and navigate into it using the terminal:
1.2 Create a Virtual Environment (Optional but Recommended)
Virtual environments help manage dependencies efficiently. Run the following command:
1.3 Install Flask
Now, install Flask inside the virtual environment:
2.1 Writing Your First Flask Application
Inside your project folder, create a new file named app.py and add the following code:
2.2 Running the Application
Save the file and run the following command in the terminal:
You should see an output like this:
Step 3: Adding HTML Templates
Flask allows you to render HTML templates using Jinja2, a powerful templating engine. Let’s create a basic HTML page.
3.1 Create a templates Folder
Inside your project directory, create a folder named templates. Then, create a file named index.html inside templates and add the following code:
3.2 Modify app.py to Render the Template
Update your app.py file to use the template:
Run the application again and refresh your browser. You should see the rendered HTML page!
Step 4: Adding Dynamic Routes and Forms
Flask allows you to handle dynamic routes and user input using forms.
4.1 Creating a Dynamic Route
Modify app.py to include a dynamic route:
4.2 Handling Forms
Step 5: Deploying Your Flask App
Once you’re happy with your Flask app, you might want to deploy it online. Popular options include:
- Heroku (Free tier available)
- PythonAnywhere
- AWS, Google Cloud, or Azure
- To deploy on Heroku, follow these steps:
Conclusion
Congratulations! You’ve just built and deployed a Flask web application from scratch. With Flask, the possibilities are endless. You can integrate databases, authentication, APIs, and more. Keep experimenting, and soon, you’ll be building full-fledged web applications effortlessly!
If you found this guide helpful, don’t forget to share it with others who want to learn Flask. Happy coding!
This content originally appeared on DEV Community and was authored by tarun
tarun | Sciencx (2025-02-09T08:56:54+00:00) How to Build a Flask Python Web Application?. Retrieved from https://www.scien.cx/2025/02/09/how-to-build-a-flask-python-web-application/
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