Qt for Python & fbs

fbs provides a powerful environment for packaging, creating installers, and signing your application, but also for managing the application’s updates. Since it is based on PyInstaller, it currently supports Linux, macOS, and Windows.

You can read the official tutorial for more details on how to use fbs, or check the documentation for a complete set of features and options.


Installing fbs can be done via pip:

pip install fbs pyinstaller==3.4

If you are using a virtual environment, remember to activate it before installing it.

After the installation, you will be able to use the fbs executable.

Starting a new project

fbs provides nice features that allow you to create a base project structure by executing the following command:

fbs startproject

This process will prompt you to answer many questions to configure the details of your project, like:

  • Application name

  • Author name

  • Qt bindings (PySide2 or PyQt5)

  • Bundle indentified (for macOS)

After the process finishes, you will have a src/ directory that will contain the following structure:

└── src
    ├── build
    │   └── settings
    └── main
        ├── icons
        │   ├── base
        │   ├── linux
        │   └── mac
        └── python

Inside the settings directory you can find a couple of json files that you can edit to include more information about your project.

The main file will be under the python directory, and its content by default is:

from fbs_runtime.application_context import ApplicationContext
from PySide2.QtWidgets import QMainWindow

import sys

class AppContext(ApplicationContext):           # 1. Subclass ApplicationContext
    def run(self):                              # 2. Implement run()
        window = QMainWindow()
        version = self.build_settings['version']
        window.setWindowTitle("MyApp v" + version)
        window.resize(250, 150)
        return self.app.exec_()                 # 3. End run() with this line

if __name__ == '__main__':
    appctxt = AppContext()                      # 4. Instantiate the subclass
    exit_code = appctxt.run()                   # 5. Invoke run()

The example will show an empty QMainWindow, and you can execute it by running:

fbs run

Freezing the application

Once you verify that the application is properly working, you can continue with the freezing process:

fbs freeze

After the process finishes, you will get a message stating the location of your executable, e.g.:

Done. You can now run `target/MyApp/MyApp`. If that doesn't work, see

Then executing the application will result in the same window you saw with the fbs run command:

cd target/MyApp/


This is the case for Linux. For other platforms like macOS, you will need to enter the directory: target/MyApp.app/Contents/MacOS, and for Windows you will find a MyApp.exe executable.