flet

library0.85.3pypypi✓ verified 86d ago

Flet is a Python framework that enables developers to build interactive, real-time, multi-platform applications using a simple Python API. It renders UI using Flutter, allowing apps to run as web apps, desktop executables, or mobile apps from the same codebase. The current version is 0.84.0, and it maintains an active and frequent release cadence, often with bi-weekly updates.

web-framework http-networking

pip install flet

github ↗package ↗homepage ↗docs ↗

INSTALL

IMPORT

SIG · FLET

flet

web-frameworkpythonv0.85.3

Install

2.7s avg

Import

2132ms

Disk

28MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.85.3 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.920 runs

installs and imports cleanly · install 0.0s · import 2.249s · 29.1MB

glibc

py 3.10–3.920 runs

installs and imports cleanly · install 2.7s · import 2.015s · 30MB

28MB installed

● package 28MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

flet

✓ import flet as ft

✗ import flet_web

The primary package is 'flet', not 'flet_web'.

Page

✓ page: ft.Page

Type hint for the Page object passed to the main function.

This quickstart demonstrates a simple counter application. It initializes a Flet page, creates a text field and two buttons, and defines event handlers to increment or decrement the counter. The `ft.app(target=main)` call runs the application, typically opening a desktop window by default.

import flet as ft def main(page: ft.Page): page.title = "Flet Counter" page.vertical_alignment = ft.MainAxisAlignment.CENTER txt_number = ft.TextField(value="0", text_align=ft.TextAlign.RIGHT, width=100) def minus_click(e): txt_number.value = str(int(txt_number.value) - 1) page.update() def plus_click(e): txt_number.value = str(int(txt_number.value) + 1) page.update() page.add( ft.Row( [ ft.IconButton(ft.icons.REMOVE, on_click=minus_click), txt_number, ft.IconButton(ft.icons.ADD, on_click=plus_click), ], alignment=ft.MainAxisAlignment.CENTER, ) ) ft.app(target=main)

flet --version

Debug

Known issues

breakingThe `delta_x` and `delta_y` attributes on `PointerEvent` objects have been deprecated and removed. Using them will result in an `AttributeError`.

fix

Replace `event.delta_x` with `event.local_delta.x` and `event.delta_y` with `event.local_delta.y`.

affects: >=0.83.1

gotchaThe correct PyPI package name for Flet is `flet`, not `flet-web`. Although Flet supports web deployment, attempting to `pip install flet-web` or `import flet_web` will lead to installation issues or `ModuleNotFoundError`.

fix

Always use `pip install flet` and `import flet as ft`.

affects: All versions

gotchaTo deploy or run a Flet application specifically as a web app, you need to configure the view and potentially use CLI commands. Simply running a Python script will often default to a desktop application.

fix

Use `ft.app(target=main, view=ft.WEB_BROWSER)` for web browser mode. For deployment, consider `flet run` or `flet publish` CLI commands.

affects: All versions

gotchaThe `page.add()` method expects a single control argument. A common mistake for new users is to pass multiple controls as separate arguments directly to `page.add()`.

fix

To add multiple controls, wrap them in a layout control such as `ft.Row`, `ft.Column`, or `ft.Stack`, and then add that single layout control to the page: `page.add(ft.Column([control1, control2]))`.

affects: All versions

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'flet_web'

Attempting to import `flet_web` or install a non-existent package `flet-web` instead of the correct `flet` package.

fix

Install with `pip install flet` and import with `import flet as ft`.

TypeError: Page.add() takes 1 positional argument but 2 were given

Trying to add multiple controls directly to `page.add()` as separate arguments.

fix

Wrap multiple controls in a layout container (e.g., `ft.Row`, `ft.Column`) and pass the container as a single argument to `page.add()`. Example: `page.add(ft.Column([control1, control2]))`.

WebSocket connection to 'ws://localhost:8550/ws' failed:

The Flet Python backend server is not running, or the specified port is blocked/already in use, preventing the client (browser or desktop app) from connecting.

fix

Ensure your Flet Python script is actively running. If the port is an issue, try running `ft.app(target=main, port=8551)` to use a different port, or check firewall settings.

NameError: name 'ft' is not defined

Forgetting to import `flet` or aliasing it as `ft` at the beginning of the script.

fix

Add `import flet as ft` at the top of your Flet application script.

Upgrade

Version history

0.85.3latest on PyPI · released Jun 8, 2026

Audit

Dependencies

No dependency data recorded yet.

Agent activity

15 hits · last 30 days

node

Resources

githubhttps://github.com/flet-dev/flet ↗

packagehttps://pypi.org/project/flet/ ↗

homepagehttps://flet.dev ↗

docshttps://flet.dev/docs/ ↗