The only junk on your phone is your "junk cleaner" app, and here's the proof

As it currently stands, Google Play is the largest mobile storefront in the world, being host to more than 2.2 million apps, just slightly more than what Apple’s App Store offers. Yet you don't see Google gloating about it much these days, despite the two companies' endless rivalry – but why? Here's a theory: in reality, that number is not a win but a disaster, and the big G knows it. And the reason for that is simple – those two million apps? Most of them are garbage.

It really is remarkable just how awful the depths of the Play Store can get and just how little policing actually occurs during Google’s app vetting process. Just search for any semi-popular app and scroll down – there, you'll find all the knockoffs with a suspiciously similar name, the copious amount of “guides” for the app, the so-called extensions which do pretty much nothing useful, and so on. Each one of these had to be approved to get to the storefront, and apparently did so without a hitch. And let’s not even start with all the malware incidents during the platform's relatively short life. What we want to discuss here, though, is something else entirely - while all of the above are real problems, most of the time they're not famous enough to warrant discussion.

However, there exists a specific type of app that somehow manages to be extremely popular despite being blatantly deceitful to its users - the so-called "cleaners", "boosters", and/or "antiviruses". Looking at a list of popular apps reveals that these so-called utilities consistently get high install rates and glowing reviews, which to us is very suspicious. So we decided to do a little investigating into what these apps actually do and why they're so popular.

Mind you, the tests we performed were far from scientific, but even then, every one of the apps we chose was obviously designed specifically to take advantage of its users, while providing no useful functionality in return. Unless you count riddling your phone with adware as useful, of course – there was plenty of that.

The existence of such scam apps is not surprising in the least – for as long as the Internet has been around, there’s been plenty of people willing to take advantage of users’ lack of technical prowess. Remember BonziBuddy? It was a piece of software, most famously in the form of a purple monkey, which was supposed to help users navigate the Web. Also, it was a nasty piece of adware, littering its users’ desktops with unwanted advertisements. The case here is almost the same, except the monkey is, thankfully, nowhere in sight – these apps advertise themselves as a real, useful utility, but in reality serve mostly as a vehicle for serving a ton of ads.

So it seems logical Google would want to get rid of such scam apps, wouldn’t it? Yes, and that’s precisely… wait, what?

How naïve of us to think a billion-dollar corporation would actually care for its users - no, the reality is that these apps rake in a ton of cash, and Google, their biggest ad provider, gets a significant cut of it. So it’s only natural for the company to want to promote them, nevermind affected consumers.

And here’s the saddest part – users love it. Just a glance at the reviews shows thousands upon thousands of misguided recommendations, with only the occasional 1-star reviewer seeing through the lies (though undoubtedly a large number of the positive reviews are fake). A particularly curious case, for example, is the one where a user was warned by their carrier about a certain junk cleaner actually being adware, which prompted them to leave a negative review on the store page. An extremely vague reply by the developer, however, was apparently enough to reverse the user’s opinion, who then proceeds to actually thank the devs. And this is just a single example - such apps are commonly advertised with misleading ads designed to scare the user into thinking they're at risk, prompting them to install a needless piece of software.

But it isn’t just Google’s fault, really – for this whole genre of scam apps to be as successful, there must be people willing to use them. And this is precisely where decades of marketing come into play – it wasn’t so long ago when a computer without some sort of antivirus installed was considered pretty much unusable online. This paranoid line of thinking – that one is always threatened online, that there’s always something wrong with their machine – seems to have stuck through the years, and now is precisely what scammers are banking on.


We analyzed five of the most popular “cleaner” apps on the Play Store, chosen from the daily list of most downloaded apps, as provided by AppAnnie. Each app was installed on a freshly reset Blu Vivo XL running Android 5.1 Lollipop. All traffic on the device was captured using Fiddler, a free network analysis tool. We spent a few minutes with each app, trying out most of its advertised features, save for those which required creating a user account or installing a separate app. 

Clean Master

The most popular app of this kind on the Play Store, Clean Master is made by the infamous Chinese developer Cheetah Mobile. Advertised features of the app include: junk file cleaning, phone boosting, antivirus, CPU cooling, and more! Actual features, however, are mostly the following: ads inside the app; ads on a second lock screen, which Clean Master labels “Charge Master” for whatever reason; ads injected into webpages when using the “safe browsing” feature; and also the constant downloading of even more ads, including videos, most of which we never actually encountered during our time with the app. Massive points for effort, however – the app almost has a few cool features, and can actually be described as somewhat pretty, though both points are quickly diminished by all the lies about "cleaning junk" and "CPU cooling". In our test, one of the first things the app did was to access several very questionable domains, including ones linked to porn and gambling sites.


It turns out math is a much more malleable concept than we previously thought, and it’s the folks at PSafe we have to thank for the realization – somehow DFNDR managed to give us “700MB speed-up memory”, despite free RAM staying at almost the same amount before and after the app’s usage. The same thing happened with its junk data removal tool, which did absolutely nothing. For what it’s worth, however, its “antivirus” did send some data to a web scanning service, but most of the time the scan consisted of downloading ads. A user review on the Play Store described the pop-up ads as “predictable”, which is nice! - it’s good knowing exactly when you’re going to be taken advantage of, in return for a mostly nonfunctional service.

Junk Cleaner

One of the two apps with the same name on the list, Junk Cleaner apparently aims to be as unobstructive as possible, immediately removing itself from the app list and becoming accessible exclusively through a persistent notification (convenient!) A feature sorely missed, however, is the decimal comma, a.k.a. the difference between 434 MB and 4.34 MB of deleted data – though this is surely just an oversight to be fixed in a future update. We can’t give it enough praise, so we’ll let its store page description do the talking: “Most of Android users suffered from the phone lagging and insufficient memory when they using their phone, if you are looking for a cleaner for your phone, Junk Cleaner will be your best choice. Free to try it now!”

SUPO Security

An app so secure, it becomes inaccessible after just one use – truly revolutionary. We actually had to install it twice, as the first time it somehow blocked access to the Play Store, while also deleting almost all traces of itself. What was left, though, were tha app's background services, which pinged the servers of QQ, a popular Chinese chat service, once every two seconds. Many users also report being bombarded with apps after installing the app, though we did not share that experience. A fun quirk of the app is just how hard it is to remove, since it asks for permissions which can effectively disable uninstalling the app, unless one knows exactly where to look.

Junk Cleaner / Junk Cleaner Lite

In the words of the developer: “Junk cleaner, professional optimize your phone performance. Make your device running like new again.” We actually started with the Lite version of the app, but quickly found ourselves wanting more functionality, of which we got plenty – though most of it consisted of, you guessed it, ads. Just like Clean Master, here we got a few problematic ad sources, including one previously linked to the distribution of Android malware, along with a ton of pop-ups, and a lock screen overlay (filled with ads, obviously). Interestingly enough, this app actually reported less RAM usage than there really was, which seems counterproductive in an app designed to lie about cleaning memory.


Unfortunately for everyone, the popularity of scam apps just like the ones we looked at is only growing bigger, in large part thanks to Google, which actively promotes them to Play Store users, along with the many device vendors who preinstall them on their phones. Even though we only tested five of the so-called "cleaner" apps, we encountered many, many more of them further down the popular apps list. When even the most widely used ones are, as we found out, complete scams, they quickly become indicative of the overall climate in this particular app niche, so while we cannot discount the existence of actual applications performing such services as advertised, we still recommend you avoid using them like the plague.



60. JitendraVS

Posts: 1; Member since: Feb 14, 2017

I'm currently using 'Clean Master' from last few years. Last month I downloaded their Anti-virus app as per their recommendation by showing 'You at a Risk'. Anti-virus app run for 4-5 days smoothly. But after that accidentally app also cleaned & deleted my 100+ important tabs in Google chrome browser. I immediately removed Anti-virus app, but unfortunately still stuck with Clean Master's app. :( I know that, alternative is in Settings > Storage > Cache data > Tap to clean. (Using UMi-eMax, Android 4.4.4, Stock version, Not Rooted).

59. egyptian3030

Posts: 30; Member since: Nov 21, 2015

Thanks for that helpful article, from my previous experience with Clean Master I agree with you this clean junk apps do nothing and I noticed that this apps are cheating us by force closing apps which will restart automatically then the CPU and memory will be work hard to operate the phone plus this apps eating battery as will. I'm using SD Maid which is really good for cleaning junk files but for memories Android OS know how it handle its memory in a good way however the best way to keep your phone light is not to install a lot of apps/games and check some apps/games reviews to check comments from real people.

52. howtech

Posts: 4; Member since: Feb 01, 2017

I never used any cleaner so far and my galaxy s7 works flawlessly

51. Ironboned

Posts: 77; Member since: Jun 16, 2016

Alert, this app is a Malware. If you don't want developers of this app see all what you have on your phone as pictures, contacts, addresses your secret stuff and your bank details stay away from this app and all kinda these apps.

49. Prabs

Posts: 22; Member since: Feb 11, 2012

Great article! This seems like it actually took time and research to uncover the truth. Would like to see more articles like this! I switched to Apple after a long time (6 years with Android) and seems like Apple vets the apps on the App Store much more than Android. What happened to "Don't Be Evil Google??" Tbh, my apps work flawlessly on my iPhone. I hate being boxed in without room to customize but everything works when I need it and I don't have my apps running malware in the background. Just sayin...

43. kevv2288

Posts: 328; Member since: Jul 30, 2015

Isn't the device maintenance that's built into the galaxy s7 powered by "clean master"? So is that system app garbage also?

45. Blazers

Posts: 796; Member since: Dec 05, 2011

Yep it's garbage. It doesn't clear all the cache like doing it through settings does.

46. kevv2288

Posts: 328; Member since: Jul 30, 2015

I'm on the 7.0 beta and it's like they want you to use the device maintenance. Because the only way to clear the cache is thru settings device maintenance and then like 4 other steps to finally clear it.

36. ilovemacs

Posts: 3; Member since: Sep 10, 2016

I'm surprised that DU Speed Booster isn't on this, because I have it on my Galaxy S 2 for T-Mobile,(don't ask.) and I get ads for other cleaners.

35. Zack_2014

Posts: 677; Member since: Mar 25, 2014

What about Samsung's Smart Cleaner crap. Not sure why they implemented that junk.

31. 10033859

Posts: 31; Member since: Jun 29, 2016

Wtf is with these people dogging on Google for giving people simple freedom.. This article seems very biased with pro-Apple agendas... Google is just giving developers freedom to do what they want and make good apps. And no they dont go around gloating how they have the worlds largest app market, because thats what Apple does. At least Google doesnt charge you 99.99$ to upload an app into the app store and 99$ more each year to keep it up... Ahem; Apple...

34. southernzombie

Posts: 358; Member since: Jan 17, 2017

Go to your room and think about what you have done. When you are less crazy you can come out.

42. marorun

Posts: 5029; Member since: Mar 30, 2015

instead of insulting with baseless crap care to say why he is wrong?

50. Prabs

Posts: 22; Member since: Feb 11, 2012

You sound like a Trump supporter. Numbers, and research, and math just don't add up to make any sense. Global warming is a hoax... That, should Google stand back when they know an app doesn't do what it says before millions of users pay money for it?

56. 10033859

Posts: 31; Member since: Jun 29, 2016

So maybe go ahead and prove why exactly im a "trump supporter".. What does numbers even have to do with this, im speaking about Apples trashed and greedy policies and keeping people from making a actual profit by charging developers 100$ to upload an app weather its free, .99$, or 50$... Your just such an idiot... Basically what your saying is because i didnt cram my comment with boring a** numbers that im a trump supporter, i dont belive in math, and SOMEHOW i dont belive in global warming... Wtf?! And what google does is trusts its developers to upload true apps, instead of forcing everyone to pay a sh*t ton of money to upload a free app. Even if you get down to the statistics, numbers, and research, Google on paper still has the best app market. Its that simple, If i wanted to upload an app to the play store, literally all i have to do is pay 25$ for privileges for life to upload whatever i want whenever i want and charge as much as i want or have it be free, then i just source a APK file and upload it. Maybe you should probably think about what your saying first, i believe your just a troll with nothing better to do, because your argument is just that stupid.

30. aaronkatrini

Posts: 242; Member since: Jun 06, 2012

Very good article, please keep up these kind of stuff, its the best, not just articles about this did this or that did that, lets go analyse sufff!!!

29. Andrewtst

Posts: 697; Member since: Jan 25, 2009

Long ago know those is junk but a lot people dunno and badly some stupid manufacturer even included it as system apps!

28. Razrman

Posts: 100; Member since: Dec 05, 2011

I wonder if the Device Maintenance feature in the Samsung Galaxy S7 Edge and the one the Note 7 had is CCleaner disguised.

44. Blazers

Posts: 796; Member since: Dec 05, 2011

On my Note 5 with T-Mobile firmware, it has this Clean Master junk built-in to the ROM.

27. PSAfromThisGuy

Posts: 146; Member since: Jan 16, 2017

Funny that it took y'all soo long to do an article on this. We know how much these apps suck and have been telling everyone that they are all a load of crap. So, thanks PA for posting something worthy of a good read.

25. tommy_vercetti

Posts: 34; Member since: Oct 10, 2016

laughs in MIUI

24. IosDroid

Posts: 117; Member since: Dec 03, 2015

The only app you need to "clean" from your phone is Facebook and you're good...

23. xondk

Posts: 1904; Member since: Mar 25, 2014

unfortunately, this happens because many people, even younger people that have grown up with computers, do not really know how they work, they may know how to use, but not how it works, unfortunately this is not likely to change. And actually seems to be increasing in my experience. Because people can just 'get' things easy via computers/phones/apps e.t.c. they aren't inclined to learn how it works. Push button get gratification.

19. piyath

Posts: 2445; Member since: Mar 23, 2012

What about CCleaner on Windows 10?? Does it work?? I think it does. But I don't use any cleaner app or anti virus app in my SGS7..

14. VLaRueC

Posts: 189; Member since: Dec 18, 2012

I agree with this article. However, how ironic it is to read about apps bombarding users with ads while fighting the website with a bombardment of ads. Only at PA..

9. AmashAziz

Posts: 2934; Member since: Jun 30, 2014

I hope the junk cleaner that comes with the phone by the manufacturer itself, is useful to some extent. On iPhone though, there's just one junk cleaner app hidden inside an app called "Battery doctor". And it does wonders to clean storage. For example, on an iPhone 5s with 136 MB of storage, running the app once cleaned about a GB of junk and made about 1.1 GB of storage available. Find batter doctor in the app store.

21. Wiencon

Posts: 2278; Member since: Aug 06, 2014

I'm pretty sure most of that crap was made by the app itself Anyway, I don't believe you, iOS apps are sandboxed and they can't remove any files other than those "owned" by the app itself You have to get jailbreak for those things

48. AmashAziz

Posts: 2934; Member since: Jun 30, 2014

Even I wouldn't have believed myself if I didn't do it. If you still don't believe me, know that it was EverythingApplePro of Youtube (with 3 million+ subscribers) who told about this hack in one of his recent videos. I don't remember the name, but it was related to top 10 iPhone hacks on something on the lines of that. Can send you a proof of what I did if you give me your email.

8. SupermanayrB

Posts: 1188; Member since: Mar 20, 2012

Stopped using apps like these & stopped advising customers of such in 2010. I just plug my phone up to my PC, multi-select the creak that's not needed (usually cache from games) & I'm good.

5. sissy246

Posts: 7129; Member since: Mar 04, 2015

I clean stuff off my phone my self.

* Some comments have been hidden, because they don't meet the discussions rules.

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