Back to: Python Programming

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While having multiple choice is great, it means that if you want to learn how to write GUI applications with Python, the first question you will need to answer is – Which library should I use?

Even though many GUI libraries are available, none has the widespread adoption of Tkinter and PyQt. So, if you’re starting with GUI programming in Python, it’ll make sense to start with one of these. There are far more tutorials, help & resources available to get you up and running, and you’re more likely to find help if you need it.

Tkinter

Best for simple tool GUIs, small portable applications

Tkinter is the defacto GUI framework for Python. It comes bundled with Python on both Windows and macOS. (On Linux, it may require downloading an additional package from your distribution’s repo.) Tkinter is a wrapper written around the Tk GUI toolkit. Its name is an amalgamation of the words Tk and Interface.

Tkinter is a simple library with support for standard layouts and widgets, as well as more complex widgets such as tabbed views & progressbars. Tkinter is a pure GUI library, not a framework. There is no built-in support for GUIs driven from data sources, databases, or for displaying or manipulating multimedia or hardware. However, if you need to make something simple that doesn’t require any additional dependencies, Tkinter may be what you are looking for. Tkinter is cross-platform however the widgets can look outdated, particularly on Windows.

Installation: Already installed with Python on Windows and macOS.

Ubuntu/Debian Linux sudo apt install python3-tk

A simple hello world application in Tkinter is shown below.

Standard code:

import tkinter as tk

window = tk.Tk()
window.title("Hello World")


def handle_button_press(event):
    window.destroy()


button = tk.Button(text="My simple app.")
button.bind("", handle_button_press)
button.pack()

# Start the event loop.
window.mainloop()

Class based code:

from tkinter import Tk, Button


class Window(Tk):
    def __init__(self):
        super().__init__()

        self.title("Hello World")

        self.button = Button(text="My simple app.")
        self.button.bind("", self.handle_button_press)
        self.button.pack()

    def handle_button_press(self, event):
        self.destroy()


# Start the event loop.
window = Window()
window.mainloop()

Outputs:

Tkinter was originally developed by Steen Lumholt and Guido Van Rossum, who designed Python itself. Both the GUI framework and the language are licensed under the same Python Software Foundation (PSF) License. While the license is compatible with the GPL, it is a ‘permissive’ license (similar to the MIT License) that allows it to be used for proprietary applications and modifications.

PyQt or PySide

Best for commercial, multimedia, scientific or engineering desktop applications

PyQt and PySide are wrappers around the Qt framework. They allow you to easily create modern interfaces that look right at home on any platform, including Windows, macOS, Linux and even Android. They also have solid tooling with the most notable being Qt Creator, which includes a WYSIWYG editor for designing GUI interfaces quickly and easily. Being backed by a commercial project means that you will find plenty of support and online learning resources to help you develop your application.

Qt (and by extension PyQt & PySide) is not just a GUI library, but a complete application development framework. In addition to standard UI elements, such as widgets and layouts, Qt provides MVC-like data-driven views (spreadsheets, tables), database interfaces & models, graph plotting, vector graphics visualization, multimedia playback, sound effects & playlists and built-in interfaces for hardware such as printing. The Qt signals and slots models allows large applications to be built from re-usable and isolated components.

While other toolkits can work great when building small & simple tools, Qt really comes into its own for building real commercial-quality applications where you will benefit from the pre-built components. This comes at the expense of a slight learning curve. However, for smaller projects Qt is not really any more complex than other libraries. Qt Widgets-based applications use platform native widgets to ensure they look and feel at home on Windows, macOS and Qt-based Linux desktops.

Installation: pip install pyqt6 or pip install pyside6

A simple hello world application in PyQt6, using the Qt Widgets API is shown below.

PyQt6

from PyQt6.QtWidgets import QMainWindow, QApplication, QPushButton

import sys


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Hello World")

        button = QPushButton("My simple app.")
        button.pressed.connect(self.close)

        self.setCentralWidget(button)
        self.show()


app = QApplication(sys.argv)
w = MainWindow()
app.exec()

PySide6

from PySide6.QtWidgets import QMainWindow, QApplication, QPushButton

import sys


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Hello World")

        button = QPushButton("My simple app.")
        button.pressed.connect(self.close)

        self.setCentralWidget(button)
        self.show()


app = QApplication(sys.argv)
w = MainWindow()
app.exec()

The code is almost identical between PyQt & PySide, so it’s not something to be concerned about when you start developing with either: you can always migrate easily if you need to.

Output:

Before the Qt Company (under Nokia) released the officially supported PySide library in 2009, Riverbank Computing had released PyQt in 1998. The main difference between these two libraries is in licensing. The free-to-use version of PyQt is licensed under GNU General Public License (GPL) v3 but PySide is licensed under GNU Lesser General Public License (LGPL). This means that PyQt is limited GPL-licensed applications unless you purchase its commercial version, while PySide may be used in non-GPL applications without any additional fee. However, note that both these libraries are separate from Qt itself which also has a free-to-use, open source version and a paid, commercial version.

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