Flask Case Study

Author: Veronika Aas, Herman Hylland, and Madelen Sletteberg

Introduction

Flask is designed as a lightweight and flexible framework that provides a solid foundation for web applications without enforcing specific tools such as database management or form libraries. Its core integrates Werkzeug for WSGI applications and Jinja2 for templating, along with standard libraries like logging. This minimalist approach allows developers to choose tools that best suit their specific needs, such as SQLAlchemy for relational databases or non-relational alternatives. Flask aims to serve as a simple bridge between Python and external tools, enabling design decisions to be tailored to each application (Flask, n.d.).

History

Flask’s story is both fascinating and unconventional, showing how something created as a joke can evolve into a widely-used and respected tool. Flask was created by Armin Ronacher in 2010 as part of an April Fool’s joke. At the time, Armin was exploring Python web development and had already worked on a larger, more complex framework called Pocco, but he felt it was overly complicated for many use cases. Inspired by the Ruby framework Sinatra, which emphasized simplicity and minimalism, Armin decided to create a similar framework for Python.

To make the launch playful, he invented a persona named Erik Lundbergh, a supposed Norwegian developer, to demonstrate Flask in a screencast. The goal of this demo was to intentionally show what not to do when using the framework. However, since he couldn’t find someone with a Norwegian accent, the character became Erik Lahavre with a French accent, voiced by a Dutch friend. The humor behind this approach added to the framework’s quirky charm (Ronacher, 2010) What started as a lighthearted experiment quickly gained traction. Developers loved Flask’s simplicity and flexibility, especially its minimalistic design that didn’t enforce specific tools or features. This allowed developers to build applications tailored to their needs, unlike larger frameworks like Django, which came with more predefined structures.

Flask’s popularity grew rapidly. By 2018, Flask had become one of the most popular Python frameworks, often tied with Django in usage, as noted in the Python Developers Survey conducted by JetBrains (JetBrains, 2018). Today, Flask continues to thrive, thanks to its active community and its ability to adapt to modern development needs through regular updates. Flask’s story reflects its core philosophy: simplicity, flexibility, and freedom for developers to make their own choices.

Biggest milestones:

Version 0.6 (June 2010): Introduced Jinja2 for templating and Werkzeug WSGI toolkit, which remain at the core of Flask.
Version 0.7 (August 2011): Added support for pluggable views and improved request and response handling.
Version 0.10 (October 2013): Improved security features, including better session handling and XSS protection.
Version 1.0 (April 2018): Marked a significant milestone with features like the updated app.run() method, enhanced CLI support, and improved error handling.
Version 1.1 (July 2019): Focused on bug fixes and increased stability.
Version 2.0 (May 2021): Introduced async support, type hinting, and other modern Python features, making Flask more robust and future-proof.

Flask’s simplicity and flexibility make it an ideal choice for both small-scale projects and complex applications, contributing significantly to its success and widespread adoption.

Key features

Lightweight: Flask is normally described as a lightweight or micro framework. It provides basic features to build web applications with minimal dependencies. Flask is often perceived to be easy to learn.
Built In Development Server: Included in this framework is a built in development server. This server comes with support for debugging and hot reloading. Thus making it easier to do tests in real time.
Routing: Flask has a basic way of routing. Flask routers are defined using the @app.route() decorator, where app is an instance of the Flask class.

from flask import Flask

app = Flask(__name__)

@app.route('/')
def home():
       return "Welcome to the homepage!"

The “ / ” is the URL pattern for the root of the application. The “ home() “ function is a function handling requests to this URL and returns a response.

Error Handling and Debugging: Flask provides detailed error messages and a debugger with an interactive console. This makes it easy for the user to identify and fix issues during development.
Templating: Flask templating is a feature that allows developers to render dynamic HTML pages using templates. The templates are files that contain static HTML code along with placeholders for dynamic content. Flask integrates with the Jinja2 templating engine to enable this.
Testing: Flask comes with a built-in test client to simulate HTTP requests and inspect responses without running the app on a server.

Market comparison

Feature	Flask	Django	FastAPI
Primary Use Case	Lightweight web apps and APIs	Full-stack web applications	High-performance APIs
Performance	Moderate	Moderate	High, due to async support
Ease of Learning	Easy for smaller projects	Steeper due to extensive features	Moderate, requires async knowledge
Built-in Features	Minimal (extensions required)	Rich features set (admin panel, auth, ORM)	Minimal (focused on APIs)
Asynchronous Support	Limited	Limited (requires 3rd party)	Built-in and optimized
Best For	Simple, lightweight apps	Full-stack, feature-rich apps	High-performance API-driven

By examining these three frameworks, developers can better understand Flask’s position in the ecosystem and how it differs in performance, scalability, and functionality compared to other popular options.

The table compares Flask, Django and FastAPI, focusing on key aspects relevant to web development. Flask is a lightweight micro framework ideal for small web apps and APIs, offering high customization but requiring extensions for additional features (Flask Documentation). Django, on the other hand, is a full-stack framework best suited for features-rich applications, with built-in tools like an admin panel and ORM, making it comprehensive but less flexible (Django Documentation). FastAPI excels in high-performance, API-driven projects with built-in asynchronous support and automatic API documentation generation (FastAPI Documentation). While Flask is beginner-friendly and Django is comprehensive , FastAPI balances modern design and performance, making it particularly appealing for API-centric use cases.

Strengths:

Lightweight: Flask is a lightweight framework with a simple and intuitive design, making it easy to learn and use, especially for beginners.
Flexibility: Flask provides a high level of flexibility, allowing developers to choose libraries and tools that best fit their needs. Rapid Prototyping: Flask is well-suited for rapid development and works particularly well for small projects and prototypes.

Weaknesses:

Lack of Built-in Features: Compared to larger frameworks like Django, Flask offers fewer built-in features, often requiring additional libraries for functionalities like database integration or authentication.
Lack of Standardization: Flask project structures can vary greatly between developers, as the framework does not enforce a fixed structure, which can lead to inconsistency in larger teams.

Why choose Flask?

Flask has gained widespread adoption among notable companies such as Netflix, Reddit, Pinterest, LinkedIn, Airbnb, and Patreon. Companies choose Flask for its simplicity, flexibility, and versatility, making it ideal for various web development tasks. Its lightweight structure supports rapid prototyping, while its extensibility allows for seamless integration and scalability. Flask is commonly used for API development, backend services, and specific web applications, as seen in companies like Netflix and Reddit. Although Flask is lightweight, its successful use in large-scale applications demonstrates its ability to support scalable architectures when paired with the right tools and strategies.

For example, Reddit uses Flask for its scalability, processing millions of user requests, authenticating users, and managing content efficiently. Pinterest leverages Flask’s lightweight design for RESTful API development, enabling smooth content uploads, searches, and user interactions.

Flask’s appeal lies in its minimalistic core, which provides developers with only the necessary tools and allows them to select additional components as needed. This simplicity makes it accessible to developers at all levels and ensures that projects remain lightweight and manageable. Flask’s flexibility and modular architecture enable developers to build tailored applications that adapt to varying requirements, whether for small prototypes or complex, large-scale systems. Its extensive documentation, community support, and rich ecosystem of extensions further enhance its value in today’s development market.

Performance and scalability

Despite its lightweight nature, Flask is highly scalable, making it suitable for applications that need to grow alongside user demands. Its scalability is achieved through a combination of built-in features and third-party tools. For instance, Flask applications can be scaled horizontally using external load balancers, which distribute incoming requests across multiple Flask instances. This setup ensures optimal resource utilization and improves responsiveness, even during traffic spikes.

To further enhance scalability, Flask supports caching systems that store frequently accessed data, such as query results or rendered templates. This reduces the need for resource-intensive database queries or computations, significantly improving response times. Additionally, Flask integrates seamlessly with scalable databases like PostgreSQL, which offer advanced features such as replication, sharding, and clustering. These features allow developers to manage higher data volumes and distribute workloads effectively as their application grows.

Flask’s performance characteristics also make it a popular choice for small to medium-sized applications, but it can handle more complex projects with the right optimization strategies. Efficient database query management is crucial to minimizing bottlenecks and maintaining application speed. Implementing caching systems like Redis or Memcached helps store commonly requested data, reducing server load and speeding up response times. By incorporating asynchronous route handlers (which Flask did from version 2.0), Flask can handle multiple requests simultaneously, improving the application’s ability to manage high traffic. Performance optimization in Flask also involves profiling the application to identify and address slow-running functions or resource-intensive areas. Load balancing can further improve performance by evenly distributing traffic across servers, ensuring consistent response times and preventing overloading.

Flask’s lightweight design, combined with these optimization strategies, allows developers to build responsive and scalable applications capable of handling increasing complexity and user demands.

Conclusion

In conclusion, Flask is a versatile yet simple and approachable framework. Its lightweight structure and modular approach enable developers to build both simple prototypes and scalable applications. Flask offers a balance of simplicity and flexibility, allowing developers to build tailored solutions. Its adaptability for use in small-scale projects and large-scale systems, as demonstrated by companies like Netflix and Reddit, underscores its scalability and reliability. While it may lack the built-in features of frameworks like Django or the high-performance focus of FastAPI, Flask strikes a balance that appeals to both beginners and experienced developers alike. As the web development landscape evolves, Flask’s commitment to simplicity and modern Python features ensures its continued relevance and utility.

Getting started

Installation info: https://flask.palletsprojects.com/en/stable/installation/#python-version

Quick start info: https://flask.palletsprojects.com/en/stable/quickstart/

Tutorial: https://flask.palletsprojects.com/en/stable/tutorial/

References:

Detimo. (n.d.). Python Flask: Pros and Cons. Gathered from: https://dev.to/detimo/python-flask-pros-and-cons-1mlo.

Famida. (2023) Top Big Companies Using Python Flask. Gathered from: https://entri.app/blog/top-big-companies-using-python-flask/

Flask. (n.d.). Flask Documentation (2.x). Gathered from: https://flask.palletsprojects.com/en/stable/

Fox, L. (2023) Why Should You Use Flask Framework For Web Development? Gathered from: https://medium.com/@lauren-fox/why-should-you-use-flask-framework-for-web-development-f5a7233e17a6

Gen. David, L. (2023) Comparison of Flask, Django, and FastAPI: Advantages, Disadvantages, and Use Cases Gathered from:: https://medium.com/@tubelwj/comparison-of-flask-django-and-fastapi-advantages-disadvantages-and-use-cases-63e7c692382a

Jayasiri, T. C. (2023) FastAPI, Flask, Django: A Comprehensive Comparison. Gathered from:: https://medium.com/@thiwankajayasiri/fastapi-flask-django-a-comprehensive-comparison-4bce6425b4ec

JetBrains. (2018). Python developers survey 2018. Gathered from: https://www.jetbrains.com/research/python-developers-survey-2018/

Mahalias, I. (2023) What Companies Use Flask? – 13 Examples. Gathered from: https://www.planeks.net/companies-using-flask/

Restack.io. (n.d.). Flask Release History. Gathered from: https://www.restack.io/p/flask-release-history. Thai, C. (2024) Performance Optimization in Flask: Tips and Tricks for Making Flask Applications Faster and More Scalable. Gathered from: https://medium.com/@christopherthai/performance-optimization-in-flask-tips-and-tricks-for-making-flask-applications-faster-and-more-07b9327277b3

Ronacher, A. (2010, April 3). April 1st Post Mortem. Gathered from: https://lucumr.pocoo.org/2010/4/3/april-1st-post-mortem/

Tutor Joes. (n.d.). History in Flask. Gathered from: https://www.tutorjoes.in/python_flask_tutorial/history_in_flask.

Official documentation for Flask: https://flask.palletsprojects.com/

Official documentation for Django: https://docs.djangoproject.com/

Official documentation for FastAPI: https://fastapi.tiangolo.com/