Opera Software ASA

Windows

The second time you run Opera, it will start displaying a dialog asking if you want Opera to be your default browser. Even if you have previously cancelled this dialog, you can change the setting by doing the following:

1. Go to Settings > Preferences > Advanced > Programs
2. Tick the checkbox for "Check if Opera is default browser on startup".
3. Next time you start Opera, answer "Yes" when the dialog asks you if you want Opera to be the default browser on your computer.

Mac OS X

You can set Opera as your default browser on your Mac by doing the following:

1. Open Safari.
2. In the Safari menu, select Preferences > General.
3. In the Default Web Browser section, select Opera.

Note: On Mac OS X 10.2, you can also select a default browser using System Preferences > Internet > Web > Default Web Browser.

Linux

For the two major desktop environments, the easiest ways of changing the default system web browser to Opera are:

Gnome

1. In Gnome's System menu, select Preferences > Preferred Applications
2. On the Web browser tab, replace the name of the current default browser with opera.
3. Be sure to leave the " %s" in the browser name field for Opera to be able to launch files passed by other applications directly.

KDE

1. Open KDE's control center.
2. Go to KDE Components > File Associations.
3. Add Opera as default application for the file types you want to launch directly in the browser, for example text/html.