A Comprehensive Comparison of the Three Major Python Web Frameworks: Which One Do You Favor? | Opinion

When you search for Python web frameworks, Django, Flask, and FastAPI consistently appear. Our latest Python developer survey results confirm that these three frameworks remain the top choices for developers using Python for backend web development. All three are open-source and compatible with the latest Python versions.
But how do you determine which web framework is best for your project? This article will explore the strengths and weaknesses of each framework and compare their performance.

Django

Django is a "batteries-included" full-stack web framework used by companies like Instagram, Spotify, and Dropbox. Hailed as "the web framework for perfectionists with deadlines," Django was designed to make building robust web applications simpler and faster.
First launched as an open-source project in 2005, Django is quite mature nearly 20 years later, yet it's still under active development. It's suitable for many web applications, including social media, e-commerce, and news and entertainment websites.
Django follows a Model-View-Template (MVT) architecture, where each component has a specific role. The Model handles data and defines its structure. The View manages business logic, processes requests, and fetches necessary data from the Model. Finally, the Template renders this data to the end-user, similar to the View in a Model-View-Controller (MVC) architecture.
As a full-stack web framework, Django can be used to build an entire web application, from the database to the HTML and JavaScript frontend.
Alternatively, you can combine Django with a frontend framework (like React) using Django REST Framework to build mobile and browser-based applications.
Explore our comprehensive Django guide, which includes an overview of the basics, a structured learning path, and other resources to help you master the framework.

Advantages of Django

There are many reasons why Django remains one of the most widely used Python web frameworks, including:

Extensive Functionality: Django's "batteries-included" approach provides built-in features such as authentication, caching, data validation, and session management. Its Don't Repeat Yourself (DRY) principle speeds up development and reduces bugs.
Easy Setup: Django simplifies dependency management by leveraging its built-in features, reducing the need for external packages. This streamlines initial setup, minimizes compatibility issues, and helps you get to work quickly.
Database Support: Django's ORM (Object-Relational Mapping) makes data handling straightforward, allowing you to use databases like SQLite, MySQL, and PostgreSQL without SQL knowledge. However, it's less suited for non-relational databases like MongoDB.
Security: Built-in defenses against common vulnerabilities like Cross-Site Scripting (XSS), SQL injection, and clickjacking can help you secure your application quickly from the start.
Scalability: While monolithic, Django still allows for horizontal scaling of application architecture (business logic and templates), caching to reduce database load, and asynchronous processing for improved efficiency.
Community and Documentation: Django boasts a large, active community and detailed documentation, providing ready-made tutorials and support. ### Disadvantages of Django Despite its many advantages, you might consider options other than Django when developing your next web application.
Not Lightweight: Its "batteries-included" design can be overkill for small applications, where a lightweight framework like Flask might be more suitable.
Steeper Learning Curve: With Django's extensive functionality comes a naturally steeper learning curve, though many resources are available to help new developers.
Performance: Django is generally slower compared to frameworks like Flask and FastAPI, but built-in caching and asynchronous processing can help improve response times.

Flask

Flask is a Python-based microframework for backend web development. But don't let the "micro" fool you; as we'll see, Flask isn't limited to small web applications.

Flask is designed with a simple core based on Werkzeug WSGI (Web Server Gateway Interface) and Jinja2 templates. Notable Flask users include Netflix, Airbnb, and Reddit.
Originally an April Fool's joke, Flask was released as an open-source project in 2010, a few years after Django. The microframework approach is fundamentally different from Django's. While Django takes a "batteries-included" approach with many features needed to build web applications, Flask is much more minimalist.
The philosophy behind microframeworks is that everyone has their preferences, and developers should be free to choose their components. As a result, Flask doesn't include a database, ORM (Object-Relational Mapper), or ODM (Object Document Mapper).
When building a web application with Flask, very little is predetermined. This can offer significant benefits, which we'll discuss below.

Advantages of Flask

Through our State of the Developer Ecosystem survey, we've seen Flask's usage steadily increase over the past five years, surpassing Django for the first time in 2021.
Reasons to choose Flask as your backend web framework include:

Lightweight Design: Flask's minimalist approach offers a flexible alternative to Django, ideal for smaller applications or projects that don't need Django's extensive features. However, Flask isn't limited to small projects and can be scaled as needed.
Flexibility: Flask allows you to choose libraries and frameworks for core functionalities like data handling and user authentication. This enables you to select the best tools for your project and scale in unprecedented ways.
Scalability: Flask's modular design makes it easy to scale horizontally. Using a NoSQL database layer can further enhance scalability.
Gentle Learning Curve: Flask's simple design makes it easy to learn, though for more complex applications, you might need to explore more extensions.
Community and Documentation: Flask has extensive (perhaps slightly more technical) documentation and a clear codebase. While Flask's community is smaller than Django's, it's consistently active and steadily growing.

Disadvantages of Flask

While Flask has many advantages, you should consider a few things before using it for your web development project.

Bring Your Own Everything: Flask's microframework design and flexibility require you to handle most core functionalities, including data validation, session management, and caching. While beneficial for flexibility, this can slow down development as you need to find existing libraries or build features from scratch. Additionally, long-term dependency management is necessary to ensure compatibility with Flask.
Security: Flask has minimal built-in security. Beyond protecting client cookies, you must implement web security best practices and ensure the security of included dependencies, applying updates as needed.
Performance: While Flask performs slightly better than Django, it lags behind FastAPI. Flask offers some ASGI support (the standard used by FastAPI), but it's more closely tied to WSGI.

FastAPI

As the name suggests, FastAPI is a microframework for building high-performance web APIs using Python. Although relatively new (first released as open source in 2018), FastAPI has quickly gained popularity among developers, consistently ranking third in our list of most popular Python web frameworks since 2021.
FastAPI is built on the ASGI (Asynchronous Server Gateway Interface) server Uvicorn and the web microframework Starlette. FastAPI adds data validation, serialization, and documentation to simplify building web APIs.

When developing FastAPI, the creators of this microframework drew on their experience using many different frameworks and tools. Django was developed before frontend JavaScript web frameworks (like React or Vue.js) became popular, but FastAPI was designed with this environment in mind.
In previous years, OpenAPI (formerly Swagger) emerged as a format for defining API structures and documenting APIs, providing FastAPI with an industry standard it could leverage.
Beyond the implicit use case of creating RESTful APIs, FastAPI is also ideal for applications requiring real-time responses, such as messaging platforms and dashboards. Its high performance and asynchronous capabilities make it excellent for data-intensive applications, including machine learning models, data processing, and analysis.

Advantages of FastAPI

In 2021, FastAPI first earned its own category in our State of the Developer Ecosystem survey, with 14% of respondents using this microframework.
Since then, its usage has increased to 20%, while Flask and Django have seen slight declines in usage.
Here are some reasons why developers choose FastAPI:

Performance: FastAPI is designed for speed, supporting asynchronous processing and bidirectional WebSockets (provided by Starlette). It outperforms Django and Flask in benchmarks, making it ideal for high-traffic applications.
Scalability: Like Flask, FastAPI is highly modular, making it easy to scale and perfectly suited for containerized deployments.
Adherence to Industry Standards: FastAPI is fully compatible with OAuth 2.0, OpenAPI (formerly Swagger), and JSON Schema. This allows for easy implementation of secure authentication and generation of API documentation.
Ease of Use: FastAPI uses Pydantic for type hints and validation, accelerating development by providing type checking, autocompletion, and request validation.
Documentation: FastAPI comes with extensive documentation, and third-party resources are continuously growing, making it accessible to developers of all levels.

Disadvantages of FastAPI

Before deciding to use FastAPI for your project, consider the following:

Maturity: FastAPI is newer and lacks the maturity of Django or Flask. Its community is smaller, and the user experience might be less smooth due to less widespread use.
Compatibility: As a microframework, FastAPI requires additional functionality to become a fully functional application. There are fewer compatible libraries compared to Django or Flask, which might require you to develop your own extensions.

Choosing Between Flask, Django, and FastAPI

So, which Python web framework is best? As with many programming endeavors, the answer is "it depends."
The right choice depends on the answers to several questions: What type of application are you building? What are your priorities? How do you expect the project to evolve in the future?

All three popular Python web frameworks have unique strengths, so evaluating them based on your application will help you make the best decision.

If you need standard web application features out of the box, Django is a good choice, suitable for projects requiring a more robust structure. Its advantages are particularly evident when using relational databases, as its ORM simplifies data management and provides built-in security features. However, for smaller projects or simple applications, such extensive features might be overkill.
Flask offers greater flexibility. Its minimalist design allows developers to pick and choose their desired extensions and libraries, making it suitable for projects needing custom functionality. This approach is ideal for startups or MVPs where requirements might change and evolve quickly. While Flask is easy to get started with, remember that building more complex applications will involve exploring many extensions.

If speed is the top priority, FastAPI is a strong contender, especially for API-first or machine learning projects. It leverages modern Python features like type hints to provide automatic data validation and documentation. For applications requiring high performance, such as microservices or data-driven APIs, FastAPI is an excellent choice. Nevertheless, it might not be as rich in built-in features as Django or Flask, and you might need to manually implement additional functionalities.

Comprehensive Comparison of the Three Python Web Frameworks

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