Build cross-platform apps in Python

   Test your app on desktop and mobile

Write integration tests with pytest and run them against your packaged app with flet test. Tap buttons, enter text, and verify user flows on desktop and mobile, with screenshot comparisons on Android and iOS.

   Build with help from AI

Explore and create apps with the AI agent in Flet Studio, or connect your coding assistant to the Flet MCP server for version-specific API information and tools to find examples and icons.

   Extensible

Build custom controls in Python by composing existing controls, or create extensions that wrap Flutter packages to add new UI components and platform integrations.

   Accessible

Add screen-reader labels, tooltips, keyboard shortcuts, and custom semantics to help more people use your app. Inspect the accessibility information your UI exposes with the semantics debugger.

Flet app example

This simple counter app displays a number in the center of the screen. Press the + button to increment it:

import flet as ft


def main(page: ft.Page):
    counter = ft.Text("0", size=50, data=0)

    def increment_click(e):
        counter.data += 1
        counter.value = str(counter.data)

    page.floating_action_button = ft.FloatingActionButton(
        icon=ft.Icons.ADD, on_click=increment_click
    )
    page.add(
        ft.SafeArea(
            expand=True,
            content=ft.Container(
                content=counter,
                alignment=ft.Alignment.CENTER,
            ),
        )
    )


ft.run(main)

To run the app, install flet:

pip install 'flet[all]'

Save the code as counter.py, then launch the app:

flet run counter.py

This opens the app in a native desktop window. The screenshot below shows it after pressing + three times:

To run the same app in your browser, add --web:

flet run --web counter.py

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Contributing

Want to help improve Flet? Check out the contribution guide.