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.

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
47 47%
53% 53
Web Frameworks
66 66%
34% 34
Python Web Framework
79 79%
21% 21
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 286 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 (286)

  • Building Weather & History Story Cards with Python and FastAPI
    By the end of this tutorial, you’ll see how I used FastAPI and Jinja2 to turn raw JSON into a dynamic timeline of weather and history that feels informative and fun. - Source: dev.to / 3 days ago
  • Build Code-RAGent, an agent for your codebase
    The only thing left to do then was to build something that could showcase the power of code ingestion within a vector database, and it immediately clicked in my mind: "Why don't I ingest my entire codebase of solved Go exercises from Exercism?" That's how I created Code-RAGent, your friendly coding assistant based on your personal codebases and grounded in web search. It is built on top of GPT-4.1, powered by... - Source: dev.to / 4 days ago
  • Understanding the Relation Between FastAPI and Uvicorn
    FastAPI and Uvicorn are two essential building blocks when developing high-performance Python APIs. - Source: dev.to / 5 days ago
  • Python: Why Quart Might Be the Better Choice over FastAPI
    Python's diverse ecosystem of web frameworks offers developers a wide range of choices for building robust and efficient applications. In the realm of asynchronous frameworks, Quart and FastAPI have emerged as popular options. While FastAPI has gained considerable attention for its speed and developer-friendly features, Quart presents a compelling alternative, especially for those already familiar with the Flask... - Source: dev.to / 15 days ago
  • Partner Models for Payments: How Rapyd Powers Partner Payment Solutions
    Let's look at how to use Rapyd to build a simple system where you can onboard merchants, add products, receive payments, and receive payouts, all powered by Rapyd's API. To fully integrate this system, businesses can sign up as a Rapyd partner to access additional capabilities for managing merchant transactions. In this tutorial, you'll see how to use the FastAPI framework in Python to create endpoints for each... - Source: dev.to / 26 days ago
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What are some alternatives?

When comparing Flask and FastAPI, you can also consider the following products

Django - The Web framework for perfectionists with deadlines

Ruby on Rails - Ruby on Rails is an open source full-stack web application framework for the Ruby programming...

ExpressJS - Sinatra inspired web development framework for node.js -- insanely fast, flexible, and simple

Laravel - A PHP Framework For Web Artisans

ASP.NET - ASP.NET is a free web framework for building great Web sites and Web applications using HTML, CSS and JavaScript.

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