pyqt4: Open website in standard browser on button click

You can also use QDesktopServices::openUrl.

Here's the minimal working example,

from PyQt5.Qt import QApplication, QUrl, QDesktopServices
import sys

app = QApplication(sys.argv)
url = QUrl("https://stackoverflow.com/questions/3684857/pyqt4-open-website-in-standard-browser-on-button-click")
QDesktopServices.openUrl(url)

you can use the python webbrowser module

import webbrowser
webbrowser.open('http://stackoverflow.com')