If you're preparing to reinstall a program or an operating system (like a clean install of Windows), you'll need to find your unique product key (CD key) or serial number before continuing.

Normally this product key is located on the original install disc, or maybe in your order confirmation email. If you've lost your product key, you can often find it in the Windows Registry but this can be difficult, or sometimes even impossible, to do. Fortunately, there are many free key finder programs available to help.

Please read our Key Finder Programs FAQ for lots of helpful information. This isn't an easy topic, especially if you're new to it.

Below are the top 20 free key finder programs. We also keep a list of commercial key finder programs but it's highly recommended that you exhaust the options below before paying for one.

Belarc Advisor

What We Like

• Finds keys for newer versions of Windows

• Also locates MS Office keys

• Shows other information about your computer

• Very small download size

• Lets you copy information to the clipboard

What We Don't Like

• Can't be used portably (you have to install it)

Belarc Advisor is the standard when it comes to system information software. I've been using this program for many, many years. One small aspect of Belarc Advisor is its ability to extract product keys for many software programs, including the one for Windows.

Advantages include a display of information in your browser window, no adware/toolbars to worry about, and an extensive list of other important computer data.

Finds Keys for Operating Systems:Windows 10, Windows 8 & 8.1, Windows 7, Windows Vista, Windows Server 2012/2008/2003, Windows XP, Windows 2000, Windows NT, Windows ME, Windows 98, and Windows 95.

Finds Keys for Other Software: Microsoft Office 2013, 2010, (plus all previous versions), Microsoft enterprise products, most programs from Adobe, Nero, Corel, and more, as well as keys for popular video games.

Please try Belarc Advisor for your software and Windows key finding needs before any other program. It's likely to provide you with the best results.

Magical Jelly Bean Keyfinder

What We Like

• Very simple interface that's easy to understand

• Will find your Windows 10 key as well as keys for older OSs

• The product keys are listed automatically so you don't have to click anything

• Product keys can be saved to a file or copied to the clipboard

• Includes advanced features like the option to view remote product keys

What We Don't Like

• Doesn't find keys for newer MS Office programs

• The program is sometimes identified as a virus in antivirus programs

• Setup tries to install other, unrelated programs along with MJB Keyfinder

The Magical Jelly Bean Keyfinder program is a free utility that retrieves product keys from the registry. It also has the ability to find product keys for Microsoft Office programs, along with product keys from many other non-Microsoft programs.

Advantages include very small size, ease of use, instant display of product keys, and multiple product key saving options.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, Windows Server 2003, Windows XP, Windows 2000, Windows ME, Windows 98, and Windows 95.

Finds Keys for Other Software: Microsoft Office 2007, Office 2003, Office XP, and several non-Microsoft programs.

The Magical Jelly Bean Keyfinder website says that this free key finder will find your Office 2010 product key but in fact, it does not, at least as of v2.0.10.13.

Winkeyfinder

What We Like

• Very easy to use

• Finds keys for Windows and Microsoft Office

• Works as a portable program

• You can save the results or print them off

• Lets you change product keys in some operating systems

• Shows results instantly

What We Don't Like

• Unable to locate the MS Office 2016 product key

• Some of the advanced options might be confusing if you're new to key finders

The Winkeyfinder program is another free utility that retrieves product keys from the Windows registry.

Advantages include small program size, no installation required, and additional features such as the ability to change registered user information.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows 2000, Windows ME, and Windows 98.

Finds Keys for Other Software: Microsoft Office 2013, 2010, 2007, 2003, XP, 2000 SP2, and 97.

Although the program doesn't state that it supports MS Office 2016, and so, therefore, shouldn't be expected to, that is one of the only Microsoft-related product keys that Winkeyfinder will not find.

Keyfinder Thing

What We Like

• Installs quickly

• Provides a very minimal and easy-to-understand interface

• Shows keys for Windows, MS Office, and other programs

• You can export the keys to save them to a file

What We Don't Like

• Shows a key for Windows 10 and 8 but it isn't correct

• Setup might try to install an unnecessary program

• Loads slower than other key finder programs

Keyfinder Thing is another free, easy to use utility that finds product keys and serial numbers hidden in the Windows registry.

Advantages include small program size, nothing to run, and support for a large list of non-Microsoft programs.

Finds Keys for Operating Systems: Windows 7, Windows Vista, Windows 2003 Server, Windows XP, Windows 2000, and Windows ME.

Finds Keys for Other Software: Microsoft Office 2007, Office 2003, Office XP, Microsoft Money, Nero, Corel Suite, The Sims, and many more programs.

Keyfinder Thing doesn't find the right product keys for Windows 10, Windows 8, or Windows NT, even though one may show up in the results. I tested it in Windows XP and didn't find issues.

Product Key Finder

What We Like

• Finds keys for Windows 7 and older OSs

• Uncluttered and minimal UI couldn't be easier to use

• Lets you export the product keys to a file

• You can also find keys from a registry file

What We Don't Like

• Doesn't show Windows 10/8 product keys

• Setup might attempt to install another program to your computer

• Includes zero advanced features (which you may or may not want depending on what you plan to do)

The not-so-originally-named Product Key Finder tool is actually a pretty good key finder program.

After executing Product Key Finder, a simple window opens displaying your Windows product key along with other product keys and serial numbers that Product Key Finder can locate.

Finds Keys for Operating Systems: Windows 7, Windows Vista, Windows Server 2008 & 2003, Windows XP, Windows 2000, Windows 98, and Windows NT.

Finds Keys for Other Software: Most Microsoft and Adobe applications, more than 200 in all according to the Product Key Finder website.

Unfortunately, Product Key Finder doesn't find keys in Windows 8 or Windows 10.

ProduKey

What We Like

• Includes all the features you'd expect in a Microsoft-based key finder tool

• Shows keys for Windows 10, MS Office, and other Microsoft programs

• Can show keys from a registry file or remote computer

• Lets you copy and export keys for backup

• You don't have to install it (it's portable)

What We Don't Like

• Unlike some key finder tools, you can't use this one to find product keys for non-Microsoft programs

• Novice users can be easily confused because results include both a Product ID and a Product Key column

ProduKey is another completely free and easy to use key finder tool.

The thing I liked best about ProduKey is how easy it is to do advanced key finder tasks like loading product keys from remote registries.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, and Windows 2000.

Finds Keys for Other Software: Microsoft Office 2013, Office 2010, Office 2007, Office 2003, Exchange Server, and SQL Server.

Everything worked fine for me with ProduKey when I used it in Windows 10 and Windows 8.

Windows Product Key Finder Pro

What We Like

• Finds keys for Windows 7 and older Windows versions, plus MS Office

• The program size is small, so it's quick to download

• The software is fully portable, so no install is necessary

• Keys display instantly without having to click any buttons

• Product keys can be backed up to a file or printed

• The application is very easy to use and read results from

What We Don't Like

• Windows 10 and Windows 8 are supposedly supported, but it won't find keys for them

• Hasn't been updated since 2013

• Confusing download page

• Only finds keys for Microsoft programs

• Security software might falsely identify it as a threat

Gear Box's Windows Product Key Finder Pro is another fantastic utility that can find your Windows product keys. It can also find product keys for several Microsoft Office programs.

Advantages include a very small download size, the ability to run it from a flash drive or other portable device, no compressed files to extract, and nothing to run to display the keys. Windows Product Key Finder Pro instantly displays product keys and allows you to save or print them for safe keeping.

Finds Keys for Operating Systems: Windows 7, Windows Vista, Windows Server 2003, Windows XP, and Windows 2000.

Finds Keys for Other Software: Microsoft Office 2013, Office 2010, Office 2007, Office 2003, and Office XP.

It's said that both Windows 10 and Windows 8 are supported, but I was unable to find the product key when I tested v2.5.

Don't let the name fool you. The 'Pro' in Windows Product Key Finder Pro doesn't mean it costs — it's actually absolutely free to use.

WinGuggle

What We Like

• Locates product keys for Windows 7 and older versions of Windows

• Finds the product keys quickly and automatically

• Keys can be copied from the program

• The program is portable

• Supports OEM editing

• Also functions as a system information tool

What We Don't Like

• Might give false product keys for Windows 10 and Windows 8

• Doesn't show keys for non-Microsoft applications

• Each time the program is started, a web page opens

• The program opens slower than similar key finder tools

WinGuggle is a very simple key finder program. WinGuggle easily finds product keys for popular Microsoft Windows operating systems and several Microsoft Office programs.

Major advantages include a quick download size, no installation required, access to a few advanced tools, and a very simple interface. WinGuggle instantly displays your Windows and Office product keys.

Finds Keys for Operating Systems: Windows 7, Windows Vista, and Windows XP.

Finds Keys for Other Software: Microsoft Office 2010, Office 2007, Office 2003, and Office XP.

Though WinGuggle supports Windows 8, Windows 10, and MS Office 2013, it, unfortunately, did not find the correct keys when I tried it.

LicenseCrawler

What We Like

• Will find product keys for Windows 10 and older newer Windows OSs

• The program is easy to use

• Also locates Microsoft Office keys

• Finds product keys for non-Microsoft programs, too

• The software is portable (no install is necessary)

• You can scan a remote computer for product keys

• Keys can be copied or saved to a file

What We Don't Like

• Unlike some product key finders, the results include lots of information that many won't find useful, such as registry information

• Lists product keys for programs that don't use one, such as Internet Explorer

LicenseCrawler is another well put together free key finder tool.

LicenseCrawler differs from other key finder programs in its almost full-text interface, which I like. I found LicenseCrawler to be very effective at finding serial numbers for the many programs on my PC.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows Server 2003, and Windows 2000.

Finds Keys for Other Software: Microsoft Office 2013, Office 2010, Office 2007, Office 2003, most Adobe products, and many more.

I was able to test LicenseCrawler in Windows 10 and Windows 8 without finding any problems.

SIW

What We Like

• Keys can be found for Windows 7, Vista, XP, and other older OSs

• Also finds product keys for MS Office and lots of other non-Microsoft programs

• Shows lots of other information about your computer

• Small download size

What We Don't Like

• Windows 10/8 are not supported

• The program no longer gets updated

• There's a lot of extra information beyond product keys, which can be overwhelming

SIW (System Information for Windows) is a portable program that displays tons of detailed information on your Windows installation and hardware devices.

Finds Keys for Operating Systems: Windows 7, Windows Vista, Windows XP, Windows Server 2003, Windows 2000, and Windows NT.

Finds Keys for Other Software: Microsoft Office 2010, Office 2007, Office 2003, Office XP and other Microsoft products as well as non-Microsoft applications like Adobe products, Norton, Nero, AutoCAD, and 150+ others

SIW is no longer in development, but even though no new updates have been released in a long while, it's still a great program.

RockXP

What We Like

• Finds the product key for Windows Vista, XP, and older Windows versions

• Locates the MS Office key in some versions of the program

• The application is portable

• Also lets you change the Windows XP product key

• A password generator is included

• Can find user passwords for some accounts on the computer

What We Don't Like

• Supports only really old versions of Windows

• Hasn't been updated in a very long time

• Your AV software might identify the program as malware

RockXP is another free program that retrieves lost product keys from the registry.

Advantages include small program size, no installation required, and additional features such as a password generator and password retriever.

Finds Keys for Operating Systems: Windows XP (officially) and also Windows Vista, Server 2003, 2000, ME, and 98.

Finds Keys for Other Software: Microsoft Office 2007 and Office 2003.

I tried running RockXP in Windows 10 and Windows 7 but none of the menus seemed to work, rendering the program useless, which means it probably works in Windows XP and Windows Vista only.

SterJo Key Finder

What We Like

• Shows product keys for MS Office and hundreds of other software programs

• Finds keys for Windows 10 and other versions of Windows

• Results are easy to understand

• Lets you search through the product key results

• Free for personal and business use

What We Don't Like

• The product key list can become overwhelming if all you need is the key for Windows

• Sometimes shows more than one product key for the same software

• Setup might try to install another program along with the key finder

SterJo Key Finder is another key finder that finds product keys for over 500 games and software on either the local Windows install (your computer) or a remote one.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows Server 2008, and Windows Server 2003.

Finds Keys for Other Software: Microsoft Office 2013, Office 2010, Office 2007, Office 2003, Office XP, Microsoft Money, Microsoft Works, and lots of other Microsoft and non-Microsoft programs like Adobe, Autodesk, Cyberlink, and others.

SterJo Key Finder is a great way to find product keys because the program is easy to read, you can search through the results, and it supports a huge number of products.

Unfortunately, SterJo Key Finder found two different product keys for one of the programs on my computer, which makes it hard to recommend above some of the other programs from this list.

Product Key Finder (OTT Solutions)

What We Like

• Results are easy to read

• Lets you save the product keys it finds

• Runs in portable mode

• Reveals the product key for Windows 7 and older Windows OSs

• You can change the Windows product key with this tool

What We Don't Like

• The last update released was in 2009

• Shows incorrect keys for Windows 10 and Windows 8

Product Key Finder won't win any creative name contests but that's not important — it's a very good key finder program.

I like Product Key Finder because it's designed very well, instantly finds product keys, allows an easy XML or CSV backup of keys found, and also lets you change your Windows registration or product key right from the tool.

Finds Keys for Operating Systems: Windows 7, Windows Vista, Windows Server 2008 & 2003, Windows XP, and Windows 2000.

Finds Keys for Other Software: Most Microsoft Office and other Microsoft programs, and many non-Microsoft applications.

I tested Product Key Finder in Windows 8 and Windows 10 but, unfortunately, the product key it showed was incorrect.

MSKeyViewer Plus

What We Like

• Locates keys for dozens of software programs

• Finds the Windows 7 key and keys for older Windows versions

• Supports some MS Office programs

• It doesn't need to be installed

• Includes other Windows information like the service pack level

• Keys can be copied to the clipboard

What We Don't Like

• Windows 10 and Windows 8 keys found by this program are most likely incorrect

• Hasn't been updated in a long time

• Advanced features are hard to access

MSKeyViewer Plus is another good product key finder program.

Major advantages include a really small size, no install needed, and super easy interface. MSKeyViewer Plus instantly displays product keys–no scanning of your registry required.

Finds Keys for Operating Systems: Windows 8, Windows 7, Windows Vista, Windows XP, Windows 2000, Windows ME, Windows 95/98, and Windows Server 2008 & 2003. 64-bit versions are also supported.

Finds Keys for Other Software: Microsoft Office 2013, Office 2010, Office 2007, Office 2003, Office XP, Office 2000, Windows Server 2012 & 2008, plus a long list of other Microsoft and non-Microsoft programs.

Though the other Windows 8 compatible programs from this list were able to find the product key for my installation, MSKeyViewer Plus wasn't able to do so.

I'd probably pick several other key finders before MSKeyViewer Plus, but if you're having trouble finding a specific key, give MSKeyViewer a try.

MSKeyViewer Plus may find a key for your Windows 10 installation, but it's probably going to be incorrect just like mine was.

Free PC Audit

What We Like

• Scans for keys automatically

• Doesn't require installation

• Shows keys for Windows 10 and other newer (and older) Windows OSs

• Identifies Microsoft Office product keys

• Shows product keys for a few non-Microsoft programs

• Includes a wealth of hardware information

What We Don't Like

• Can seem cluttered if you're not interested in all the other results

• The initial auto-scan might take a while to complete

• You can't export just the product key information to a file

Free PC Audit is a system information tool that shows not only hardware information but also product keys for several Windows and Microsoft Office installs.

It's very small, completely portable, scans automatically, and lets you easily copy out product keys.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, and probably older versions as well.

Finds Keys for Other Software: Microsoft Office 2013, Office 2010, 2007, Office 2003, and likely some older versions, as well as some Adobe and Corel software.

Because there's so much other information shown in Free PC Audit, it can seem very cluttered if you're using it just for finding product keys.

Windows Product Key Viewer

What We Like

• Supports recent and old versions of Windows

• Results are clear and easy to read

• Shows additional information beyond the product key

• No need to install the program (it's portable)

• The key can be copied to the clipboard

What We Don't Like

• When printing or exporting, you can't save just the product key; all the other information is included as well

Windows Product Key Viewer is another key finder program that shows the product key for several versions of Windows.

You can easily copy the product key out of the program, print the keys, or save them to a file. Additional details are shown as well, such as the product ID, install date, and build number.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows 2000, Windows ME, Windows 98, Windows 95, and Windows Server 2008/2003

Due to Windows Product Key Viewer's small size and portability, it's a great product key finder to store on a flash drive.

Lazesoft Windows Key Finder

What We Like

• Finds the Windows 10 key and keys for other newer and older Windows OSs

• Locates Microsoft Office keys

• Very portable (small download size and no installation necessary)

• The program interface is extremely easy to use

• The key can be saved to a file or the clipboard

What We Don't Like

• Some MS Office keys can't be found even though they're listed as being supported

• Doesn't show keys for non-Microsoft programs

Lazesoft Windows Key Finder is another free program that can find the product key for many Windows installs and Microsoft Office versions.

The program is small, completely portable, and simple to read. You can print or save the product keys to a file.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows 2000, and Windows Server 2012/2008/2003.

Finds Keys for Other Software: Microsoft Office 2016, 2013, Office 2010, Office 2007, Office 2003, and Office 2000.

Though Microsoft Office 2013 and 2016 is supported, I was unable to use Lazesoft Windows Key Finder to locate those keys in Windows 10, Windows 8, or Windows 7.

Product Key Informer

What We Like

• Finds product keys for some versions of Windows and MS Office

• The keys are easy to read

• Lets you save the keys to the clipboard

• Able to search the network for product keys on other computers

• Entirely portable (no installation necessary)

What We Don't Like

• Supports older software only

• Doesn't let you back up the product keys to a file

Product Key Informer is another free product key finder program but it finds product keys for only a few Microsoft programs other than the operating system.

Finds Keys for Operating Systems: Windows 7, Windows Vista, Windows XP, Windows 2000, Windows ME, and Windows 98.

Finds Keys for Other Software: Microsoft Office 2007, Office 2003, and Office XP.

Honestly, I didn't care much for Product Key Informer. I think it was the baked-in fields for specific product keys that bothered me. It's a waste of screen real estate and confirms that the program's product key finding abilities are very limited.

Windows Product Key Finder

What We Like

• Locates keys for Windows 7 and older Windows versions

• The download size is small

• You don't have to install the program

• The key can be copied

• Shows other useful OS information

What We Don't Like

• Although the software technically works in newer versions of Windows, the product key it finds is not correct

• Doesn't show the key automatically

• You can't save the product key to a file

Windows Product Key Finder is only 80 KB in size, is completely portable, and quickly shows the product key.

Finds Keys for Operating Systems: Windows 7, Windows Vista, and Windows XP.

When compared to other key finder programs from this list, Windows Product Key Finder is extremely basic and void of support for anything but the Windows OS. Also, while it is able to open in Windows 8 and 10, the product key it finds is inaccurate.

Game Key Revealer

What We Like

• Finds the keys for a huge variety of video games

• Lets you export the product keys to a file

• The application is 100 percent portable

• Supports changing the key for some games

What We Don't Like

• Doesn't show product keys for any other kinds of software

• Hasn't been updated since 2014, so it might not support newer games

Game Key Revealer shows the product keys of over 2000 games.

It's completely portable, takes up very little space, and can export keys to a text file or print them off.

Finds Keys for Games: Half-Life, Battlefield 2, Counter-Strike, Mirror's Edge, Halo, Need for Speed, Dead Space, Crysis, Harry Potter, and many more.

In addition to showing the product keys for a few thousand games, keys for nearly two dozen can actually be changed with Game Key Revealer, which could come in handy.

Abelssoft's MyKeyFinder

What We Like

• Works in Windows 10 and older Windows versions

• Shows keys for MS Office programs and some non-Microsoft applications

• You can block areas of the registry where you don't want to scan for keys

• Multiple ways to save the keys

• You can find keys quickly by searching through the results

What We Don't Like

• Takes a while to scan for product keys

• Might show keys for programs that don't use product keys

• Not all features are free; you have to pay to enable them

• Asks you to donate each time you close the software

MyKeyFinder lets you save product keys to a PDF file or to the clipboard. You can also send one or more keys to a printer.

You can search through the list of install keys it finds and even blacklist registry keys to avoid finding serials in those locations.

Finds Keys for Operating Systems: Windows 10, Windows 8, Windows 7, Windows Vista, and Windows XP.

Finds Keys for Other Software: VMware, some Microsoft Office products, and others.

While testing MyKeyFinder, I found that a scan takes much longer to complete than any of the other programs from this list. Also, it found keys for programs (hundreds of them) that don't actually use serials, as well a key for Microsoft Office 2013 that wasn't correct.

Important Product Key Finder Information (Windows Product Keys)

If your system was purchased with Microsoft Windows pre-installed and you have not reinstalled it or upgraded it yourself, a key finder may only find the generic product key that your PC manufacturer used to install Windows. This product key may not work when attempting to reinstall Windows. In this case, you must use the unique product key that is on the sticker attached to your computer case.

If you can't locate your product key sticker you'll need to request a new Windows product key.