We’ve long railed against registry cleaners and system tuners as useless products that waste your money, but how do you go about cleaning up after uninstalling shady freeware? Answer: You don’t. You avoid installing nonsense on your PC to begin with by testing everything in a virtual machine first. Snapshots just make it easier.

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It’s been a long time since the days when you could just test out lots of freeware on your computer without worry — these days almost all freeware is bundled with spyware, crapware, adware, or the ninth circle of hell, which includes things like the awful Ask Toolbar or the terrible Trovi browser hijacker malware. That’s why we almost never recommend software downloads unless they are from a really reputable place like SysInternals (Microsoft), Ninite, or NirSoft.

Every other download site is either wrapping crapware-filled freeware with their own crapware, or they are just distributing installers full of crapware. Some of them will only bundle the crapware if you are using Internet Explorer — so you think you’re recommending a clean source to your family because you’re using Chrome, only to help them get infected because they are still on IE. Even open-source software isn’t safe from the awful — SourceForge now bundles some pretty terrible crapware with a lot of their downloads, and that’s just the “safe” sources.

But you can still get all of your freeware testing fun without worrying about malware problems. Just install it into a virtual machine instead. That’s what we do.

What You Should Know About Virtual Machine Software

When it comes to virtual machine software, there are a lot of choices, but not all of them provide a way to make it easy to test software and then roll back to a clean state in a couple of seconds. Sure, you could always reinstall Windows over and over, but who wants to do that?

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The answer is to use the snapshot feature provided in some virtual machine software — You simply create a snapshot after installing and configuring the virtual machine, and then you install anything you want, and then you can roll it back to the snapshot as if nothing ever happened.

If you’re running Windows, Virtualbox is probably your best bet. It’s free, open-source, runs on Windows, Mac, and Linux, the interface is easy to use, and it supports snapshots. There are other solutions, but VMware Player don’t support snapshots, Hyper-V supports a similar feature called “checkpoints” but has a really clunky interface, and while VMware Workstation has snapshots and is easy to use, it’s fairly expensive for what we’re trying to accomplish. We’d stick with Virtualbox.

Editor’s Note: If you’re running OS X and want to test out some Windows software, we’d recommend getting a copy of Parallels, which is our favorite virtual machine solution. It’s not free, but it’s a lot faster than Virtualbox, integrates really well into OS X, and it even supports Aero transparency in Windows. And, of course, it has really great support for snapshots.

Once you’ve selected your solution, there are a couple of things that you need to keep in mind:

Don’t Enable File Sharing: If you are testing out some shady software in a virtual machine and it ends up including malware, you don’t want to run the risk of the malware spreading to your host PC through a shared folder. Don’t Use Bridged Mode: Most of the time the default for a virtual machine is to hide it behind a virtual NAT (network address translation) network that keeps the virtual machine at least partially isolated from the rest of the network. What you don’t want to do is use bridge mode, where the virtual machine connects directly to your main network. Don’t Use Your Regular Accounts: It should go without saying, but if you are using Windows 8 you shouldn’t sign into the virtual machine using your regular Microsoft account. The same goes for Google or any other accounts. If the freeware contains some type of spyware, you don’t want it to be able to get access to your accounts.

You probably want to avoid running actual malware in a virtual machine unless you completely shut down the VM network connection, but for testing freeware that might have spyware or adware included, a virtual machine will be a very safe solution.

Acquiring an Operating System for Your Virtual Machine

Now that you’ve selected your virtual machine software, and you know what you need to properly virtualize without allowing a possible infection to spread, it’s time to go about installing an operating system inside of your virtual machine. There’s just one small problem… Windows isn’t free.

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If you have an extra license for Windows, you can go ahead and install a copy into your VM, and if you don’t have access to the install media anymore, you can legally download Windows 7, 8, and 8.1, or you could join the Windows Insider program and use Windows 10 as your testbed for free until the final version is released.

If you don’t have an extra license for Windows, you can still download Windows media and use Windows 7 in trial mode, or you can get a trial version of Windows 8.x Enterprise if you don’t mind signing up for it. Or again, you could use Windows 10 in a virtual machine and kill two birds with one stone by learning Windows 10 while testing interesting freeware.

Using Snapshots in Your VM to Test Software

For this example we’re going to show how to use snapshots in Parallels, because that’s what we use here at How-To Geek, but you can do the exact same thing in VirtualBox, as you can see in the screenshot above. You can also read our full guide to using snapshots in VirtualBox if you get lost.

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We’re also going to assume you can figure out how to install Windows into a VM. If you still aren’t sure of yourself, we’ve got a beginner’s guide to using virtual machines that should help you out.

Step 1: Take a snapshot.

Whether you are using Parallels or VirtualBox, get your virtual machine to the clean state that you want, and then take a snapshot to preserve things exactly the way they currently are. In this case, take note of the open Notepad window in my Windows 7 VM.

Step 2: Install Whatever You Want

Seriously, you can install whatever you want. Even something that you probably shouldn’t install… it’s a virtual machine, after all. We’re going to head straight for the worst download site and try something that sounds sketchy. And we’re going to click Accept on everything, because why not?

After just one download and clicking Accept twice, all of our browsers have been hijacked and some sketchy PC cleaner app is telling you that your PC has loads of errors. Never mind that it’s a fresh VM that hasn’t had anything installed on it except for Chrome — it just goes to illustrate that these apps are all scams.

It’s definitely time to roll back these changes.

Step 3: Roll the VM Back to the Clean Snapshot

In Parallels the Revert to Snapshot is on the Actions menu, but VirtualBox is just as simple: you can right-click on the VM in the list and use the revert option there.

Step 4: There is No Step 4

There’s nothing left to do. It only takes a few seconds (depending on your hardware) to roll back the VM to the previous state. As you can see in the screenshot below… that means the current state including all applications running in the same place that they were. It’s like the Windows Hibernate Mode on super steroids.

Both VirtualBox and Parallels actually let you make multiple snapshots and switch between them at will. It’s an amazing feature that you should really start using. For more amazing features, check out our guide to the 10 Virtualbox tricks you should know about.

And from now on, don’t load any sketchy software on your main PC, alright?