Software Alternatives, Accelerators & Startups

Flask VS FastAPI

Compare Flask VS FastAPI and see what are their differences

Flask logo Flask

a microframework for Python based on Werkzeug, Jinja 2 and good intentions.

FastAPI logo FastAPI

FastAPI is an Open Source, modern, fast (high-performance), web framework for building APIs with Python 3.6+ based on standard Python type hints.
  • Flask Landing page
    Landing page //
    2023-07-24
  • FastAPI Landing page
    Landing page //
    2023-05-14

Flask features and specs

  • Simplicity
    Flask is a micro-framework, meaning it is lightweight, easy to understand, and simple to use. It requires minimal setup to get a web application up and running.
  • Flexibility
    Flask provides flexibility and control over the application's architecture, allowing developers to choose the components they need and avoid unnecessary bloat.
  • Extensibility
    Flask supports various extensions to add capabilities like database integration, form validation, and authentication without compromising its core simplicity.
  • Documentation
    Flask has comprehensive and well-organized documentation, making it easier for developers to learn and implement features effectively.
  • Community
    Flask has a large and active community, providing ample resources like tutorials, code snippets, and third-party libraries that can help speed up development.
  • Testing
    Flask is designed to be unit tested easily, allowing developers to test their applications and ensure reliability.

Possible disadvantages of Flask

  • Scalability
    Flask may not be as scalable as some other frameworks for very large applications due to its minimalist design and lack of built-in features.
  • Boilerplate Code
    Since Flask requires you to integrate and configure many components manually, codebases in Flask can sometimes contain a lot of boilerplate code.
  • Opinionated Architecture
    While Flask provides flexibility, it also means there are fewer conventions. Developers must make more architectural decisions, which can be challenging for large team collaboration.
  • Limited Tools
    Compared to more comprehensive frameworks, Flask offers fewer built-in tools and features, which may necessitate additional plugins or custom implementations.
  • Learning Curve for Complex Applications
    While Flask is easy to learn for simple applications, it can become complex to manage as the application grows, requiring a good understanding of design patterns and software architecture.

FastAPI features and specs

  • High Performance
    Built on Starlette and Pydantic, FastAPI is one of the fastest frameworks for Python, providing high performance due to its asynchronous request handling.
  • Automatic Interactive API Documentation
    FastAPI automatically generates interactive API documentation via Swagger UI and ReDoc, which are very helpful for development and testing.
  • Type Checking and Validation
    With Pydantic models and Python type hints, FastAPI provides automatic data validation and type checking, reducing the chance of runtime errors.
  • Ease of Use
    Its syntax and design make it easy to learn for Python developers, offering a smooth development experience while reducing boilerplate code.
  • Asynchronous Support
    FastAPI supports asynchronous programming, allowing for better performance for I/O-bound operations, making it optimal for handling many simultaneous connections.
  • Extensive Documentation
    It has comprehensive and well-structured documentation, which is very useful for both beginners and advanced users.
  • Community and Ecosystem
    FastAPI has a growing community and ecosystem, with many plugins and integrations available to extend its functionality.

Possible disadvantages of FastAPI

  • Learning Curve for Asynchronous Programming
    Although FastAPI itself is easy to learn, grasping the concepts of asynchronous programming in Python can be challenging for beginners.
  • Complex Dependencies
    Using Pydantic for advanced validation can make the request models complex, requiring a deeper understanding of Pydantic and its functionalities.
  • Early Stage Libraries
    Some third-party libraries and extensions specifically tailored for FastAPI might still be in early stages of development and lack long-term stability.
  • Limited Real-World Examples
    Although the documentation is extensive, there might be limited real-world examples and case studies readily available compared to more mature frameworks.
  • Deployment Complexity
    Deploying FastAPI applications might be more complex in comparison to traditional synchronous frameworks, mainly due to the need for asynchronous server setups.

Analysis of Flask

Overall verdict

  • Flask is a good choice for developers looking for a lightweight and flexible framework for building web applications, particularly if they value simplicity and control over out-of-the-box features.

Why this product is good

  • Flask is a microframework for Python, offering simplicity and flexibility, making it a good choice for small to medium-sized applications.
  • It has a simple core with easy-to-add extensions, allowing developers to customize their applications as needed.
  • Flask's lightweight nature means it has a small overhead, leading to faster development cycles and easier debugging.
  • It has a strong community and excellent documentation, providing ample resources for learning and troubleshooting.

Recommended for

  • Developers who prefer Python and want a minimalist approach to web development.
  • Those working on small to medium-sized applications or microservices.
  • Developers who appreciate a modular and extensible architecture.
  • Teams that require rapid prototyping or quick deployment cycles.

Analysis of FastAPI

Overall verdict

  • FastAPI is widely regarded as a good choice, especially for applications that require high performance, scalability, and modern Python features. It is suitable for both simple and complex projects, making it a versatile tool in the web development ecosystem.

Why this product is good

  • FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.7+ based on standard Python type hints. It is built on top of Starlette for web framework capabilities and Pydantic for data validation and settings management. FastAPI is known for its excellent performance, automatic generation of interactive API documentation (with Swagger and Redoc), and support for asynchronous programming. Developers appreciate its ease of use, detailed documentation, and helpful error messages.

Recommended for

  • Developers building RESTful APIs
  • Teams looking for a high-performance ASGI-based web framework
  • Projects that require asynchronous programming capabilities
  • Applications needing automatic generation of interactive API documentation
  • Python developers who prefer utilizing type hints for code clarity and validation

Flask videos

Built To Last A Life Time - Ragproper Modern Glass Flask Review

More videos:

  • Review - The Hip Flask Guide - Gentleman's Gazette
  • Review - 10 Best Flasks 2019

FastAPI videos

FastAPI from the ground up

More videos:

  • Tutorial - 30 Days of Python - Day 14 - Web App with Flask, FastAPI, ngrok, and Invictify - Python TUTORIAL
  • Review - [PT] Python - API com FastAPI - Chat | twitch.tv/codeshow

Category Popularity

0-100% (relative to Flask and FastAPI)
Developer Tools
46 46%
54% 54
Web Frameworks
64 64%
36% 36
Python Web Framework
78 78%
22% 22
API Tools
0 0%
100% 100

User comments

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Reviews

These are some of the external sources and on-site user reviews we've used to compare Flask and FastAPI

Flask Reviews

The 20 Best Laravel Alternatives for Web Development
Flask is the micro that’s got your back without trying to run the show. It comes with the essentials but trusts you to pick your tools — no baggage attached, truly Pythonic at heart.
Top 9 best Frameworks for web development
The best frameworks for web development include React, Angular, Vue.js, Django, Spring, Laravel, Ruby on Rails, Flask and Express.js. Each of these frameworks has its own advantages and distinctive features, so it is important to choose the framework that best suits the needs of your project.
Source: www.kiwop.com
25 Python Frameworks to Master
You’ll also have access to some extension packages like Flask-RESTful, which adds support for building powerful REST APIs, and Flask-SQLAlchemy, a convenient way to use SQLAlchemy in your flask app.
Source: kinsta.com
3 Web Frameworks to Use With Python
Flask is a micro web framework for building web applications with Python. Here is the official web page of Flask.
Top 10 Phoenix Framework Alternatives
Flask is a micro-framework, i.e., it does not bundle tools and libraries and instead uses third party libraries to deliver functionalities.

FastAPI Reviews

The 20 Best Laravel Alternatives for Web Development
FastAPI, as the name hints, is a swift mover. Built on Starlette, it’s all about speed and performance with Python. Crafting API masterpieces at the speed of light, now that’s something.
25 Python Frameworks to Master
Since its release in 2018, it has rapidly gained popularity due to its great performance and simplicity. In fact, according to PyPi Stats, FastAPI has over 9 million monthly downloads, surpassing even full-stack frameworks like Django.
Source: kinsta.com
3 Web Frameworks to Use With Python
myapp/ is the main directory of your FastAPI application. It includes all the other files and directories needed for the application.static/ is a directory used to store static assets such as CSS, JavaScript, and image files. These assets are served directly by the web server and are typically used to add visual styling and interactivity to the application.css/, img/, js/...
Best Alternatives to FastAPI App Free for Windows (2021)
FastAPI Alternative – So many alternatives app to FastAPI that you must to know out there. And, looking for an ideal software was not easy matter. Lucky you, at this page you can find the best replacement app for FastAPI. So what you are waiting for, get the latest FastAPI alternative app for Windows 10 from this page.
Top 5 Back-End Frameworks to Consider for Web Development in 2021
FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.6+ based on standard Python type hints. It is fast when compared to other major Python frameworks like Flask and Django. FastAPI gives great flexibility to fulfill businesses’ API needs in today’s evolving world.

Social recommendations and mentions

Based on our record, FastAPI should be more popular than Flask. It has been mentiond 289 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.

Flask mentions (42)

  • PSET 9 Finance - What is "disable response caching" and the function they ask to notice
    "After configuring Flask, notice how this file disables caching of responses (provided you’re in debugging mode, which you are by default in your code50 codespace), lest you make a change to some file but your browser not notice. ". Source: about 2 years ago
  • How to Send an Email in Python
    Flask, which offers a simple interface for email sending— Flask Mail. (Check here how to send emails with Flask). - Source: dev.to / over 2 years ago
  • Plotting Bookmarks with Flask, Matplotlib, and OAuth 2.0
    Lang="en"> Plot Bookmarks!{% block title %}{% endblock %} rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" /> class="container"> Plot Bookmarks by Date {% block containercontent %}{% endblock %} /> class="footer"> class="text-muted"> >This is a... - Source: dev.to / almost 3 years ago
  • Determining what version of Flask is installed
    What's the easiest way to determine which version of Flask is installed? Source: about 3 years ago
  • What is the point of uWSGI?
    I'm looking at the WSGI specification and I'm trying to figure out how servers like uWSGI fit into the picture. I understand the point of the WSGI spec is to separate web servers like nginx from web applications like something you'd write using Flask. What I don't understand is what uWSGI is for. Why can't nginx directly call my Flask application? Can't flask speak WSGI directly to it? Why does uWSGI need to get... Source: about 3 years ago
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FastAPI mentions (289)

View more

What are some alternatives?

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Yii Framework - Yii is a high-performance component-based PHP framework best for Web 2.0 development.