If you run the free version of the popular temporary file cleaner and system tool CCleaner for Windows, you may have noticed that it has started to display advertising popups on the system.

I noticed the behavior after installing CCleaner 5.44 on a Windows 10 Pro system; it is possible, however, that older versions of CCleaner display the advertisement as well.

The advertisement appears as a popup message in the lower right corner of the screen. It highlights a Summer Sale and a discount for CCleaner Professional.

You can upgrade to the professional version of CCleaner for 50% off.

It reads:

Summer Sale: Get 50% off!

Treat your computer to automatic cleaning for a stress-free summer

The offer ends on July 7.

Note that the popup is displayed when you run the portable version or the version that gets installed on the system.

The popup message disappears after a few seconds but you can open the upgrade option in the CCleaner interface to display the offer again.

There you may notice that the 50% may not have been accurate. On my system, it displayed a discount of €10 from €24.95 to €14.95 which is less than 50%.

The reason why there is a discrepancy is that a click on the "upgrade & save" button opens a page on the CCleaner website. There you find the offer for €12.49 instead of $14.95.

It is rather strange that Piriform/Avast would display two different upgrade offers to users of the program. You can open the Summer Sale page directly here.

CCleaner Professional adds features such as priority customer support, automatic cleaning, and additional cleaning options to the application.

There is no option in the program to disable the advertising popup. In fact, there is no option at all to prevent this kind of behavior.

What you can do is block CCleaner's Internet access. If you disallow the program to connect to the Internet. for example with TinyWall or Windows Firewall Control, it seems that you won't get the advertising popup.

The one downside to this is that you will have to download new versions manually to install them, at least until the July 7 deadline is reached.

There is no telling, however, whether the popup won't be used to advertise other Avast products such as Avast antivirus products.

CCleaner has been in the news recently quite a bit. Avast acquired CCleaner's parent company Piriform in 2017, and servers were compromised in 2017 shortly after the acquisition. The company added privacy options to CCleaner in 2018 which caused initial confusion as well.

Closing Words

I have to admit that I don't mind reminders like the one that CCleaner displays. What I dislike about it is that there is no option to turn it off and that the popup is displayed frequently and not just once or on user request.

Users who dislike the practice may want to check out alternatives such as Bleachbit.