8 Ways To Identify Unknown File Types

Saikat Basu 16-04-2013

unknown file typeThe problem with unknown file types is not their obscurity. The concern is that they may be dangerous. The threat comes from email attachments, unsecured flash drives, and the old one – rash downloads. Downloading an unknown file type is just as dangerous as downloading from an unknown source. Unknown file types can be benign of course, but what if they are potential landmines? Identification before action should be the way to go for the nimble witted. Identifying unknown file types is always a recommended security precaution.


Finding out the right file type also helps you fix broken file associations How To Change & Fix Broken File Type Associations In Windows 7 This article will discuss what file type associations are, how you can change them in general, and why so many people have issues with .lnk file associations in Windows. If you have been running into... Read More . Once you know the nature of a specific file, you can pair it with the right program. There are free tools which help to change or remove file type associations 2 Best Tools To Change Or Remove File Type Associations [Windows] Having unused file types associated with software that you don't use isn't a big deal, but some of us are a little OCD with our Windows. That's fine, and we should have that control. Now,... Read More for you. Then there are software like Free Opener Say Open Sesame And View More Than 80+ File Types With Free Opener [Windows] Which is the very first file viewer or editor you go for after a fresh install? Some asked our wider community the same question - What is the best universal file viewer? A few worthies... Read More which are like universal file viewers. But a word to the wise – always go back to the basics when you come across a file type which is new to you. Find out more about it. There is no shortage of methods to identify unknown file types. Here are eight of them…

Go Online…Start With The Good Old Google Search

unknown file type

Google knows everything. I think it does know about all file types too as it sources the details from a few sites we will discuss here. So, using Google to find out all about a file type is a no-brainer. You can also dive into the other sites on the result page to find out more about the file. Pretty much any search engine can handle these queries. Don’t forget to put a dot before the file type.

Wolfram Alpha

unknown file type finder

Even after writing about 10 Search Terms To Put Wolfram Alpha To Good Use Everyday 10 Search Terms To Put Wolfram Alpha To Good Use Everyday Read More , I am still trying to fathom the power of this computational knowledge engine. Well, Wolfram Alpha is one resource you should always tap to dig out arcane statistics. Finding out about a mysterious file type is one of its more dull uses. Enter the file extension and click on compute. Wolfram Alpha does its data juggling and gives you brief but sufficient information like the type of file and compatible applications that can open it. There were some really rare file formats which Wolfram Alpha couldn’t fully describe.



unknown file type finder

Eight times out of ten, this is the reference website that will crop up on a Google search for a file type. FILExt is a file extension reference library for a mindboggling variety of file types. The site has an alphabetical index of nearly 1526 extensions. The total database is far more extensive – 26,024 records in the main database; 51,537 registered file type records; and 16,344 records in the Program/MIME type database. So, a better idea would be to use the Google Custom Search box on top.

Each file type gets its own page where the extension is detailed. The pages also may contain a link to scan your PC for invalid entries, but I would suggest that you ignore that and just use the site for its information. As it is, programs which claim to speed up your PC should be thoroughly vetted before use.


unknown file type finder

Advertisement is another online database for searching file extensions. The database is kept updated by the site developers and also through user contributions. You can scroll down and see the latest file types that have been added. You can also navigate to the browser page and drill down to an extension by category. The page that details the extension also gives you related extensions of that type. The same page also links you directly to the specific application needed to open the file type.

File Info

identify unknown file type

File Info is a comprehensive site that gives you quite a few tools to grab file type information from its database. You have the neatly categorized directory of different file extensions. File Info also gives you browser plug-ins for Chrome and Firefox. You can also download a File Extension Lookup Desktop Gadget for Windows and a File Extension Lookup Dashboard Widget for Mac. I think its bit of an overkill for normal users, but File Info covers the bases quite well. File Info also helps to identify unknown file types with the File Identifier. File Identifier is a 468 KB download that basically acts like a search shortcut when Windows fails to identify an unknown file type.

identify unknown file type


File-Extensions is a similar site but not as extensive as Filesuffix. But I feel it’s better organized. File types are also indicated with their icons. One of the enriching features on the site is the availability of articles concerning day to day file operations. Opening unknown file types under Windows or Why I can’t send or receive some files via email, are some of the common queries answered here with the help of descriptive articles.


identify unknown file type

You might solve the mystery of the unknown file extension, but then comes the second part – how to open that particular file without spending a dime. takes care of the dilemma by giving you a neatly categorized list of file types and the relevant free software programs that can open them. As the homepage says – There are plenty of great programs out there that will cost you hundreds of dollars to do what you need. What you probably don’t know is that there is usually free software that is just as good. You just don’t know about it.

Other online databases you can look into:


A Free Utility – TrID 

8 Ways To Identify Unknown File Types trid

It’s one thing to decipher an unknown extension. It’s another thing altogether to have a completely unknown file in your hands (without even a clue of an extension). In such extreme cases, you can turn to a little freeware utility called TrID. TrID uses a file’s binary signature to identify its type. Binary signature bytes are unique to file types and can be used to identify or verify a file. TrID has a library of file type definitions that can be matched against any unidentified file. The program and the definition package have to be downloaded separately, but both are lightweight. You need .NET framework installed for it to run.

unknown file type

TrID is a command line utility but it also comes with a GUI version called TrIDNet and an online tool – TrID Online. You can choose one depending on your comfort level. But the command line tool is more flexible as it allows you to use wildcards and know the probability score for a file type. Wildcards can also be used to scan an entire folder or a group of files. This comes handy when a bunch of files are recovered using some file recovery tools and you need to ascertain their unknown file types.

The program hasn’t changed much since we last reviewed it except for the database which keeps on expanding with new inclusions of file type definitions. The latest one has 5041 file types indexed. . Our archived post Identify Unknown Files with TrID Identify Unknown Files with TrID [Windows/Linux] Read More shows you how to use TrID. It is as simple as pointing to the unknown file, then allowing the program to scan it.

Have You Been Stumped By A Strange File Extension?

Identifying unknown file types is one of those little needs that can strike us in the middle of a normal computing day. It helps to know that there are so many resources you can depend on to understand what a file does and which is the application needed to handle it. Have you been befuddled by a strange file type? Which one was it? Do you know of any other resource to add to this list?

Image Credit: 3D Rendering via Shutterstock

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  1. Praveen pandey
    April 22, 2013 at 9:31 am

    thanks for tips

  2. Keith Swartz
    April 18, 2013 at 6:31 am

    Awesome read on a MUCH needed subject. Keep up the GREAT output, Saikat &!

  3. null
    April 17, 2013 at 3:52 pm

    Google always works for me.

  4. Catherine M
    April 17, 2013 at 10:48 am

    This list I am sharing, so many of my friends have files they cannot identify and they panic. So now they can figure it out for themselves (maybe). Thanks for another good article.

    • Saikat Basu
      April 17, 2013 at 5:25 pm

      Welcome Catherine. Glad the article helped :)

  5. Robert Clark
    April 17, 2013 at 10:33 am

    I'd strongly recommend TrID as it is checking the actual file - useful where a user may have added the wrong extension onto a file and then can't unsderstand why they can't open it. I've had this quite often especially with Word Tables where the user thinks they were working with an Excel spreadsheet and saves it with a .xls extension.

    • Saikat Basu
      April 17, 2013 at 5:27 pm

      Precisely. TrID is extremely useful when a file does not have a file extension in the first place or it may be wrong and the supposed software is not able to open the file.

  6. Rafael
    April 17, 2013 at 8:30 am

    The end of this article is a surprise!
    TrID is a really interesting tool!

  7. Chris Marcoe
    April 17, 2013 at 6:06 am

    I've always just Googled anything I was unsure of. And i don't think I've run into an extension that I couldn't ID that way. But this is great info and I'll have it for future use. thank you.

  8. Nevzat A
    April 17, 2013 at 6:03 am

    Superb article. As an advanced user I also use Hex viewers & editors to see the contents directly when I find such an unknown file.

  9. james
    April 17, 2013 at 5:40 am

    .a52 might be a multi part file. try looking up *.a

  10. Rama Moorthy
    April 17, 2013 at 5:07 am

    thank god . its not .ASS !! fbstream

  11. Josue Aguilar
    April 17, 2013 at 4:45 am

    Thank you for your explanations. I knew some but there are a couple that I didn't. So thanks I've learned something new

  12. dragonmouth
    April 16, 2013 at 9:12 pm

    Thanks for the article. I only knew of Now you have provided other sites that will demystify the mysterious file extensions.

  13. dragonmouth
    April 16, 2013 at 9:10 pm

    Neither Wolfram Alpha nor knew what ".a52" extension was. I wonder what else they do not know about? :)

    • james
      April 17, 2013 at 5:53 am

      based on my quick googling it might be an Atari 5200 ROM for use in emulation or it might be a Dolby Digital Audio File or it might just be some random extesion the devs put on the file to confuse you if it's dolby audio you should be able to open in in VLC if it's a rom try thoring it at an Atari 5200 emulatior like kat5200 or Rainbow 2.0

      • dragonmouth
        April 17, 2013 at 11:08 am

        Thanks for the answer but the other sites DID know what that file extension was. All I meant was that those two sites may not be as reliable for extension info as the other ones Saikat mentioned.

      • Saikat Basu
        April 17, 2013 at 5:22 pm

        Correct. Google says it is an Atari 5200 Game Image file. describes it here -

    • Saikat Basu
      April 17, 2013 at 5:19 pm

      Give it time. Wolfram Alpha has its uses. We have written a few posts on it explaining some of its more offbeat uses :)