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Best free PC cleaner for your computer in 2021

Man using desktop PC
(Image credit: Gorodenkoff / Shutterstock)

There are many free PC cleaners and optimizers that claim to deliver noticeably faster performance, but not all live up to the hype. That's why we've tested all the most popular options and rounded up the ones that we believe will give your PC a noticeable speed boost, with no hidden extras or intrusive ads.

With Windows 11 on its way on October 5, it's best to make sure that your PC is ready for the upgrade, as long as it meets the minimum requirements.

The best free PC optimizer available today is Iolo System Mechanic – a feature-packed toolkit containing everything you need to purge unnecessary files, fine-tune your PC's settings and protect your privacy at the same time. However, if your needs are more straightforward, we've also rounded up four other excellent tools that will give your PC a thorough spring clean without offering an intimidating number of options.

It's worth noting that you can do much of what these free PC optimizers do yourself using Windows' built-in system maintenance tools, but that's time consuming; what's really being sold here is convenience.

If you want more features, many of these free PC optimizers also have premium counterparts that can perform more advanced tasks, and offer additional tools like secure file deletion and scheduled scans.

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(Image credit: Iolo)

1. Iolo System Mechanic

Enjoy a faster, cleaner PC with the best PC optimizer

Specifications
Operating system: Windows
Reasons to buy
+One-click cleanup+Clear, detailed analysis+Choice of scan types
Reasons to avoid
-Some features premium-only

Update: A recent change to Iolo's checkout process means you will be automatically subscribed to a $19.99 (about £15 / AU$25) per month support package when you purchase a product. This is a very large extra charge, so make sure to double-check before entering your payment details.

Iolo System Mechanic removes junk files and unwanted apps, blocks bloatware and unwanted auto-run settings, clears out RAM and wipes various logs, browser histories and caches.

Not only does this free up key system resources, it also eliminates traces of your browsing activity to protect your privacy.

Its PC optimization toolkit really does make a difference; whenever we've tested System Mechanic we've found a significant speed improvement, especially at startup. The free edition is excellent, but the two premium versions – System Mechanic and System Mechanic Pro – are well worth considering if you find yourself using it regularly – and Iolo is offering a 70% discount with the voucher code TECHRADAR.

The genuine performance boost we saw after running System Mechanic made it our favorite PC optimizer. Read on for four more of the best apps around for speeding up your Windows PC.

(Image credit: Restoro)

2. Restoro

Streamlined PC optimizer with utilities repair

Reasons to buy
+Great essentials+Fast, efficient scans+Very competitive prices
Reasons to avoid
-Limited free version

Restoro doesn’t boast the biggest feature list we’ve seen, but it does a great job of providing the essentials and managing those well without adding too many unnecessary extras. 

Numerous problems are scanned for, listed if found, and repaired with the powerful system repair tool. All Restoro scans include built-in malware detection. Any suspicious files will be immediately identified, and you can decide whether or not they need to be removed.

If you have one of the two unlimited use plans, you will benefit from the power of Restoro’s excellent real-time monitoring tools. These are designed to help you keep tabs on your computer, identifying potentially dangerous apps or security breaches before any damage is caused. 

This should be quite self-explanatory, but Restoro’s full money-back guarantee basically means that you can request a full refund if you’re not happy with the program’s performance. 

The only negative is that the free version allows you to run the software, but not any of the repair tools.

(Image credit: IObit)

3. IObit Advanced SystemCare Free

A hands-off approach to optimization that's ideal for novice users

Specifications
Operating system: Windows
Reasons to buy
+Clean, customizable interface+One-click and auto cleanup
Reasons to avoid
-Can't exclude individual files-Extra software in installer

IObit Advanced SystemCare comes in two forms: a free edition version that covers basic house cleaning, and a Pro version that adds internet speed-boosting, real-time optimization, privacy protection, deep registry cleaning and 24/7 technical support. That's US$20 (about £15, AU$25) for a year, and the license covers three PCs.

Whichever edition you choose, IObit Advanced SystemCare's interface is well designed, easy to use and unlikely to frighten even the newest PC user. We'd deduct points for an installer that wants to add additional programs - that's hardly in keeping with the philosophy of keeping unwanted stuff off your computer - but they're easy to avoid if you choose a custom installation.

Like most of the PC optimizers here, it cleans up files and folders you don't need, neatens up the Windows registry and corrects errors on your hard drive – all via a simple, slick dashboard.

(Image credit: CCleaner)

4. Piriform CCleaner

Eliminate unnecessary files, clean the registry and manage apps

Specifications
Operating system: Windows, macOS, Android
Reasons to buy
+Frees up disk space+Easy to use+For desktop and mobile
Reasons to avoid
-Duplicates many Windows tools

Piriform CCleaner has been around for a long time, and part of the reason for its ongoing popularity is that it cleans the parts of your PC that many other free system optimization tools don't.

There's a paid-for version of the optimization toolkit that adds real time protection and cleanup scheduling, but the free edition of CCleaner covers the important stuff such as removing temporary files, getting rid of browser caches, removing unwanted cookies while keeping the useful ones and so on.

If your PC just feels sluggish then this is the free PC optimizer to try first. It doesn't have all the advanced features of apps like System Mechanic, but the stuff it does clear is famous for slowing down PCs.

(Image credit: Ashampoo)

5. Ashampoo WinOptimizer 2019

A fast scanner plus a suite of well designed maintenance tools

Specifications
Operating system: Windows
Reasons to buy
+Quick, thorough scans+Descriptive interface+Comprehensive toolkit
Reasons to avoid
-Adds store links to desktop

Ashampoo WinOptimizer's biggest selling point is its flexibility – you can scan for junk files, broken registry entries and browser cookies with a single click, and erase them all with one more.

Alternatively, you can dive deeper by selecting the 'Details' button to review the results of your scan one by one. Unlike some PC optimizers, Ashampoo WinOptimizer gives you a full description of each issue it's identified, explaining exactly what it is, and why you should consider removing it. You can then make an informed decision about whether to erase or keep it.

WinOptimizer also includes a suite of 'modules' for routine maintenance tasks like defragging hard drives and optimizing startup processes. These are all tasks that could be accomplished within Windows itself, but having them all in one location is much more convenient than trawling through menus.

(In case you're wondering, Ashampoo takes its name from this optimization software, which cleans your PC 'like a shampoo'.)

(Image credit: Razer)

6. Razer Cortex

Made to help gamers wring extra performance from their PCs

Specifications
Operating system: Windows
Reasons to buy
+Frees up RAM for games+Provides FPS stats+Frequently updated
Reasons to avoid
-Contains some unnecessary extras

If your system struggles when you're trying to get your game on, Razer Cortex could well be the answer. This free PC optimizer suspends unnecessary system processes, clears out memory and defrags your system to get the very best game performance possible.

Razer Cortex is available for Windows 7, 8 and 10, and while the differences won't make you jump up and down in astonishment - for most people the results will mean slightly smoother visuals rather than astonishing performance improvements - it does automate the fiddly process of turning off unnecessary software and services when it's time to play.

Daryl Baxter

Daryl had been freelancing for 3 years before joining TechRadar, now reporting on everything software-related. In his spare time, he's written a book, 'The Making of Tomb Raider', alongside podcasting and usually found playing games old and new on his PC and iPad. If you have a story about a newly-updated app or one that's about to launch, drop him a line.