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CCleaner logo 2013.png
CCleaner Software Screenshot.jpg
CCleaner 5.6 running on Microsoft Windows 7
Developer(s) Piriform
Initial release23 September 2003;17 years ago (2003-09-23)
Stable release(s) [±]
Windows5.80.8743 / 25 May 2021;9 days ago (2021-05-25) [1]
macOS1.18.30 / 5 October 2020;7 months ago (2020-10-05) [2]
Android5.6.2 / 31 May 2021;3 days ago (2021-05-31) [3]
Written in C++
Operating system Windows 7 and later, [4]
OS X Mountain Lion and later, [4]
Android Lollipop and later
Platform IA-32 and x64
Available in58 languages
List of languages
Albanian, Arabic, Armenian, Azeri (Latin), Belarusian, Bosnian, Brazilian Portuguese (Portugues do Brasil), Bulgarian, Burmese, Catalan (Catala), Chinese (Simplified), Chinese (Traditional), Corsican, Croatian (Hrvatski), Czech (Ceský), Danish, Dutch (Nederlands), English, Estonian (Eesti keel), Farsi, Finnish (Suomi), French (Français), Galician, Georgian, German (Deutsch), Greek, Hebrew, Hindi, Hungarian (Magyar), Indonesian, Italian (Italiano), Japanese, Kazakh, Korean, Kurdish, Latvian, Lithuanian (Lietuviu), Macedonian, Malaysian, Marathi, Mongolian, Norwegian, Polish (Polski), Portuguese (Portugues), Romanian (Romana), Russian, Serbian (Cyrillic), Serbian (Latin), Slovak, Slovenian, Spanish (Espanol), Swedish (Svenska), Tatar, Thai, Turkish (Türkçe), Turkmen, Ukrainian, Vietnamese. [5]
Type Utility software
License Freemium for home use; commercial for use in organisations and institutions [6]

CCleaner ( /ˈsklnər/ , originally Crap Cleaner), [7] developed by Piriform (a company acquired by Avast in 2017), is a utility used to clean potentially unwanted files and invalid Windows Registry entries from a computer. It is one of the longest-established system cleaners, first launched in 2004. [8] It was originally developed for Microsoft Windows only, [9] but in 2012, a macOS version was released. An Android version was released in 2014.


CCleaner has been reviewed by, [10] TechRadar, [11] PC Magazine , [12] and TechRepublic. [13]


CCleaner can delete potentially unwanted files left by certain programs, including Microsoft Edge, Internet Explorer, Firefox, Google Chrome, Opera, Safari, Windows Media Player, eMule, Google Toolbar, Netscape, Microsoft Office, Nero, Adobe Acrobat, McAfee, Adobe Flash Player, Sun Java, WinRAR, WinAce, WinZip and GIMP [14] along with browsing history, cookies, recycle bin, memory dumps, file fragments, log files, system caches, application data, autocomplete form history, and various other data. [15] The program includes a registry cleaner to locate and correct problems in the Windows registry, such as missing references to shared DLLs, unused registration entries for file extensions, and missing references to application paths. [14] CCleaner 2.27 and later can wipe the MFT free space of a drive, or the entire drive.

CCleaner can uninstall programs or modify the list of programs that execute on startup. [16] Since version 2.19, CCleaner can delete Windows System Restore points. [17] [18]


CCleaner was first launched in 2004 for Microsoft Windows. [8] It remained a Windows-only utility until 2012. On 2 June 2011, Piriform announced a public beta test program for CCleaner for Mac. [19] The Mac version graduated to the test stage on 30 January 2012. [20]

A commercial Network Edition was also introduced. Piriform released CCleaner for Android in 2014. [21]

Critical reception

CNET editors gave the application a rating of 5/5 stars, calling it a 'must-have tool'. It was awarded Editor's Choice Award in April 2009 by CNET. [22] In 2016 Piriform announced 2 billion CCleaner downloads worldwide. [23] In January 2014 it had been the most popular software on FileHippo for more than a year, and had a 5-star editor's rating on and Softpedia. [24] Softmany select as featured App and give 5 star to it is an outstanding utility to free up hard disk space from unnecessary data. [25] CCleaner has been reviewed by , [10] TechRadar , [26] PC Magazine [27] and TechRepublic . [13]

Data collection

Upon its release, the Active Monitoring component of CCleaner 5.45 incorporated a data collection module that collected information from computers without the consent of their owners. Piriform claims that it did not collect personally identifiable information. After criticism later versions allowed data collection to be controlled separately by the user, although data collection is still on by default. [28] [29] [30] [31]

Bundled software

In December 2018, it was reported that users installing CCleaner would also have Avast Antivirus installed without their permission, with TechSpot claiming this arguably made CCleaner no better than the malware it was supposed to defend against. Piriform denied this. [32]

In July 2020, Microsoft Windows Defender began flagging the free version of CCleaner as a "potentially unwanted application", stating that "while the bundled applications themselves are legitimate, bundling of software, especially products from other providers, can result in unexpected software activity that can negatively impact user experiences." [33]

Malware infection

After Piriform was acquired by Avast, in September 2017, CCleaner 5.33 was compromised by the incorporation into the distributed program of the Floxif trojan horse that could install a backdoor, enabling remote access to 2.27 million [34] infected machines. [35] [36] Forty of the infected machines received a second-stage payload that appears to have targeted technology companies Samsung, Sony, Asus, Intel, VMWare, O2, Singtel, Gauselmann, Dyn, Chunghwa and Fujitsu. [37] [38] On 13 September, Piriform released CCleaner 5.34 and CCleaner Cloud 1.07.3191, without the malicious code. [39]

On 21 October 2019, Avast disclosed a second security breach during which attackers tried again to insert malware inside CCleaner releases. That attempt was unsuccessful. [40]

Related Research Articles

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Antivirus software Computer software to defend against malicious computer viruses

Antivirus software, or anti-virus software, also known as anti-malware, is a computer program used to prevent, detect, and remove malware.

Clam AntiVirus

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