Software Alternatives, Accelerators & Startups

Flet VS FastAPI

Compare Flet VS FastAPI and see what are their differences

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Flet logo Flet

Build internal web apps quickly in the language you already know.

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.
  • Flet Flet Studio
    Flet Studio //
    2026-06-23
  • FastAPI Landing page
    Landing page //
    2023-05-14

Flet features and specs

  • Single code base for any device
    Your app will equally look great on iOS, Android, Windows, Linux, macOS and web.
  • Build an entire app in Python
    Build a cross-platform app without knowledge of Dart, Swift, Kotlin, HTML or JavaScript - only Python!
  • 150+ built-in controls and services
    Beautiful UI widgets with Material and Cupertino design: layout, navigation, dialogs, charts - Flet uses Flutter to render UI.
  • 50+ Python packages for iOS and Android
    Numpy, pandas, pydantic, cryptography, opencv, pillow and other popular libraries.
  • Full web support
    Flet apps run natively in modern browsers using WebAssembly and Pyodide, with no server required. Prefer server-side? Deploy as a Python web app with real-time UI updates.
  • Built-in packaging
    Build standalone executables or bundles for iOS, Android, Windows, Linux, macOS and web. Instantly deploy to App Store and Google Play.
  • Test on iOS and Android
    Test your project on your own mobile device with Flet App. See your app updates as you make changes.
  • Extensible
    Easily wrap any of thousands of Flutter packages to use with Flet or build new controls in pure Python using built-in UI primitives.
  • Accessible
    Flet is built with Flutter which has solid accessibility foundations on Android, iOS, web, and desktop.
  • Community and Documentation
    Extensive, well-maintained documentation and an active global community of developers.
  • Flet Studio
    An online development environment featuring a gallery of runnable, editable, and shareable examples that helps developers learn, prototype, and collaborate directly in the browser.

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 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

Flet videos

Flet Tutorials

More videos:

  • Tutorial - Flet + Python: Build a Cross-Platform App (Desktop | Mobile | Web) in 30 Minutes
  • Tutorial - Flet Tutorials

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 Flet and FastAPI)
Application And Data
100 100%
0% 0
Developer Tools
6 6%
94% 94
API Tools
0 0%
100% 100
Development Tools
100 100%
0% 0

Questions & Answers

As answered by people managing Flet and FastAPI.

What makes your product unique?

Flet's answer

Flet enables developers to build web, desktop, and mobile applications from a single Python codebase without requiring frontend frameworks, while offering a rich set of built-in UI controls, instant deployment, and an integrated online playground with runnable examples.

How would you describe the primary audience of your product?

Flet's answer

Python developers, data scientists, educators, startups, and software teams looking to build modern cross-platform applications quickly without needing frontend development expertise.

Which are the primary technologies used for building your product?

Flet's answer

Python, Flutter, Dart, FastAPI, WebSockets, and modern web technologies. Flet combines Python on the backend with Flutterโ€™s rendering engine to deliver cross-platform applications for web, desktop, and mobile from a single codebase.

Why should a person choose your product over its competitors?

Flet's answer

Flet has an exceptionally low learning curve, allowing developers to build real web, desktop, and mobile applications with Python and see results in minutes. A single codebase runs across all major platforms, with built-in packaging and deployment support, helping developers move from idea to production faster and with less complexity than traditional cross-platform frameworks.

User comments

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Reviews

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

Flet Reviews

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FastAPI Reviews

  1. Kurslog team
    ยท Working at Kurslog ยท

    When our backend team needs to build services for data parsing, aggregators, or high-load APIs, FastAPI is our absolute go-to choice. It completely lives up to its name-development speed is outstanding.

    The combination of Pydantic for data validation and built-in async support keeps our shared codebase clean, strictly typed, and reliable. But the biggest highlight for our cross-functional team is the automatic generation of interactive OpenAPI (Swagger) documentation. Our frontend and mobile developers no longer have to wait for backend engineers to manually update API docs; everything stays perfectly in sync automatically. It has drastically improved our team's communication and delivery speed.

    ๐Ÿ Competitors: Django, Flask, ExpressJS, Nest.js, Spring Boot
    ๐Ÿ‘ Pros:    Blazing fast performance (on par with nodejs and go)|Native asynchronous support out of the box|Automatic, interactive documentation generation (swagger/redoc)|Strict typing and data validation with pydantic
    ๐Ÿ‘Ž Cons:    Smaller plug-and-play ecosystem compared to older frameworks like django|Requires our architects to design the project structure and directory layout from scratch

The 20 Best Laravel Alternatives for Web Development
FastAPI, as the name hints, is a swift mover. Built on Starlette, itโ€™s all about speed and performance with Python. Crafting API masterpieces at the speed of light, now thatโ€™s something.
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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 โ€“ 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 businessesโ€™ API needs in todayโ€™s evolving world.

Social recommendations and mentions

Based on our record, FastAPI should be more popular than Flet. It has been mentiond 311 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.

Flet mentions (43)

  • The text mode lie: why modern TUIs are a nightmare for accessibility
    > a locked down GUI that is efficient to use and designed to display the data that the commandline tools produce [...] You can have all that. There are various data presentation tools out there (one I can think of right now is Streamlit as I tried it out a few months ago, but I'm not really a data person, Python is just my primary language). For a more general GUI framework that's pretty easy to use and still full... - Source: Hacker News / 3 months ago
  • Add Authentication and SSO to Your Flet App
    Creating cross-platform applications has become much easier with frameworks like Flet. Flet allows developers to build modern web, desktop, and mobile apps using Python. Its simplicity and flexibility help developers focus on creating great user experiences without having to worry about platform-specific complexities. - Source: dev.to / 3 months ago
  • MicroPythonOS graphical operating system delivers Android-like user experience
    Interesting. Would want to see this going on actual Android. Especially since I have a few Python GUI projects going which I intend to use on Android (but currently using flet). https://flet.dev. - Source: Hacker News / 6 months ago
  • FletX: Bring Reactive Power to Your Python UI with GetX-Like Simplicity
    Meet FletX โ€” a lightweight framework built on top of Flet that brings reactivity and clean architecture to Python GUI apps. - Source: dev.to / about 1 year ago
  • From Codecademy to Programming: My First Python Flet App For Managing Shopping List
    As part of my final project for the "Fundamentals of Programming" in Codecademy Computer Science course, I wanted to build something practical that could also help me reinforce my understanding of programming fundamentals. With that in mind, I created a simple but fully functional shopping list app using Fletโ€”a Python framework for building beautiful UIs without needing to dive into web development. This app... - Source: dev.to / about 1 year ago
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FastAPI mentions (311)

  • Shipping Sovereign SDK: Cryptographic Forensic Receipts and the End of the AI "Prose Tax"
    The Sovereign SDK is a Python-native framework designed to minimize prose overhead while generating ironclad, cryptographic execution receipts for AI agents, complete with drop-in FastAPI/Starlette ASGI middleware. - Source: dev.to / about 2 months ago
  • 5-Minute AI Jobs and Closed Tabs โ€” Why We Built Replay-Then-Tail SSE
    We had a feature in production where a single user request could run for five-plus minutes โ€” fetch documents, chunk them, hit an LLM per chunk, synthesize a final answer. We did the obvious thing first: a FastAPI handler that ran the pipeline and streamed progress back to the browser over Server-Sent Events. - Source: dev.to / 3 months ago
  • FastAPI With LangChain and MongoDB
    FastAPI is a Python framework for building APIs quickly, efficiently, and with very little code. - Source: dev.to / 3 months ago
  • I Built A " CrowdSense AI " : A Scalable, Context-Aware Platform for Smart Stadiums
    Backend: Python-based FastAPI for its asynchronous I/O capabilities and rapid JSON serialization. - Source: dev.to / 3 months ago
  • Async PyMongo in FastAPI
    FastAPI is a high-performance web framework that is production-ready and designed for building APIs in python, with roots embedded in asynchronous programming. It embraces Pythonโ€™s asyncio model as its core principle rather than treating it as optional. This design choice gives FastAPI leverage for I/O bound workloads such as db access, external API calls and real-time data streaming. - Source: dev.to / 3 months ago
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What are some alternatives?

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

Kivy - Open source Python framework for rapid development of applications that make use of innovative user interfaces, such as multi-touch apps. Installation on WindowsInstallation on Windows. Installation; What are wheels .

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

Flutter - Build beautiful native apps in record time ๐Ÿš€

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

BeeWare - Write your apps in Python and release them on iOS, Android, Windows, MacOS, Linux, Web, and tvOS...

Django - The Web framework for perfectionists with deadlines