Skip to main content

Customizing web app

When you open Flet app in the browser its index.html, Flutter engine, favicon, images and other web app resources are served by Flet Server (aka "Flet daemon" or fletd). These resources are bundled with flet Python package. However, there are situations when you need to modify the contents of certain files to customize appearance of your app or its behavior, for example:

  • Favicon.
  • App loading animation.
  • manifest.json with PWA details.
  • index.html which includes app description and touch icon.

You can specify assets_dir in call to set the location of assets that should be available to the application. assets_dir could be a relative to your directory or an absolute path. For example, consider the following program structure:


You can access your images in the application as following:

import flet as ft

def main(page: ft.Page):


To override favicon with your own put favicon.png file into the root of assets directory. It should be a PNG image with the size of at least 32x32 pixels.

Loading animation

To override Flet animation image put icons/loading-animation.png image with your own app logo into the the root of assets directory.

If you like to completely customize Flutter app initialization logic you can modify Flet's original index.html following the instructions in Flutter documentation. A customized index.html must be placed in the root of assets directory.