Open UNKNOWN File Extension  Guide ▷ 2020

When we have several files on our computer and we do not know their origin, use, nor what programs to use to open it, the first thing that may cross our mind is to delete those types of files.

But here we bring you a better option, instead of deleting them use the list of websites and programs that we leave in this post in order to know the type of extension that this file has and which programs are compatible with them and thus download them.

In this list are one of the 10 most used websites by people on the internet, that is to say that they are some of the best. Some with better functions than others, but all useful, which respond to any need.

How to know the format of everything we download from the Internet?

There are different formats, which we download every day. They all have an abbreviation to be able to identify them, but this does not mean that because we can do it, our computer will always do it too, so you must have the appropriate programs for each of them.

In order to identify them, it is necessary that we first know their extensions, because these are divided into different formats. Most files have the following extensions:

For graphic files

Graphic files are all those that contain images inside, basically they are all those that we use to save photos:

  • Gif: They are a kind of image files with enormous quality, but due to their quality they take up more space than JPG formats. These are mostly animated image files.
  • Jpg: This format is the one most commonly used for photographs as it is the one that best compresses images. You can reduce images from 1MB to 0.1MB.
  • Tif: This is the most commonly used format for printing images on image paper.
  • Bmp: Also known as a bitmap, used by Windows for wallpaper images, it is these that it uses for the desktop background.
  • Png: This format has many utilities, the difference of this format is that it allows images without a background, and with different qualities.
  • Mix: This is the image format issued by Microsoft Office’s PhotoDraw.

Text files

Text file extensions are all those that we use to save written files as documents and the like:

  • Txt: these are a type of plain text files. This format is present in most programs, and therefore it is compatible with most of them.
  • HTML / .htm: this is the text format used to encode languages ​​and designs for webs and other similar ones, which is read by browsers.
  • Doc: these are documents issued by Microsoft Word.
  • Pdf: This is so called due to its acronym in English Portable Document Format, this type of format is compatible today with most programs, and even browsers like Google Chrome can read it.
  • EML: this is a format for identifying emails. They are rare because few people often download email messages.
  • RTF: This is a format the same as the .doc extension, the difference is that it is more compressed and takes up less space than .doc files
  • : this type of format is for PostScript printers.

Compressed and encoded files

These extensions are the ones used to identify files compressed by programs like WinRar or WinZip:

  • Zip and Rar: This is the format for compressed files, compatible with few programs, very useful to transport large information in few spaces.
  • Arc and Ari: they are also compressed files, although today they are hardly used anymore.
  • Bin: these types of files compress binary-encoded programs.
  • Exe: These are executable files for Windows, when you run them, Windows Explorer starts it, decoding everything it contains.

Audio files

Audio extensions possibly the most confusing of all since there are many formats, however the most used currently are:

  • Au Y Aiff: these are sound formats used at Apple.
  • Mp3: These are very famous formats, which is why they are already compatible with most software and programs. Dedicated to the world of music.
  • Ra: this format can only be played by Real Player which is a program that can be found on the Internet.
  • Wav: this format can be played with Windows Media Player.

Video files

With video extensions It is the same as with the previous ones; there are many formats that have been created so far, but again the most used are the ones we mention here:

  • Avi: It is the Microsoft format and is played with Windows Player.
  • Mov: These are Apple formats and are only played by QuickTime.
  • Mp4 / mpeg These are video formats used with the MPEG compression system for all Operating Systems.
  • Mkv: Matroska is a video format widely used today in the film and television industry. It is an independent format that does not belong to any specific program, but it can be read by most video players.
  • FLV: This is a format used to identify videos to be played on online media such as websites or web applications. It was designed for Adobe Flash Player, in which it is no longer widely used.

Other files

This section is for certain special formats that do not quite fall into the categories mentioned above, so we place them in this:

  • Ppt Y PPTX: this is the format used to identify those files created in Microsoft Power Point.
  • Xls Y XLSX: These are file formats emanating from Excel.
  • Mdb: They are database files, which is read by Microsoft Access.

List of the best websites and tools to view files with unknown extension

Another way to know what type of files you have and with what application or programs to open them is by using the following websites and tools.



This is a page that can answer any questions regarding how to open a file and which programs to use. Its query mode is very simple, you just have to load the file from your computer, and when it is fully loaded click on “Check the file type”.

The next link will take you to the web.



To search a database of extensions, this is the best option. You can search by adding letters of the alphabet to the database, or also search by extension type, or just go to the category of the most used extensions. This database is very complete and easy to use for any user.

Follow the next link to access the web.


file info

This is another excellent extension search engine, its interface and page layout makes it very similar to Google, with a box that allows you to write the extension which you are going to consult, or just the name that Windows mentions that it is. It divides its enormous information on extensions by categories in order to facilitate searches of the file and in turn of the compatible program.

The next link will take you to the web.



As Wikipedia is always present in everything, here we leave it, is that this is a place that thanks to its enormous information you can find the different extensions that you know us, in addition, it specifies you and often directs you to the necessary programs to be able to download and open the files.

The next link will take you to the web.

Open With

open with

This is a web page, with similar functions to those mentioned above, so it allows you to do a direct search or just search by the category where this type of file is found. Each of the extensions has a custom tab where it explains from the origin to the free programs that are compatible with them. This has a version for desktops in access from computers.

Follow the next link to access the web.

Media Info

media info

This program can help you a lot to recognize files, since it has a great information content which can guide you and describe any extension you have in mind, from what to do with that file, how to use it, which program to use that is compatible with it, up to the rate or bit rate, and in the case of videos the frame rate.

The next link will take you to the web.



This is one of the most popular pages which offers the file and extension identification service. In it, you can find a huge number of extensions and check the one you want to know and even get the type of applications or programs to use to open the file. It is very and comfortable for all people, giving explicit and necessary details to be able to understand each of the extensions that you have in mind.

The next link will take you to the web.

Wolfram Alpha


Wolfram is a fabulous website that will answer any question about those extensions you don’t know. This online tool that searches for any information you give it, with a fast and effective result, giving important details of each extension. Among its results it leaves a list of those software compatible with the extensions and its link to download it.

Follow the next link to access the web



Finally, we leave TrIDNet which is a program that is considered old, but this does not mean that the information it stores is obsolete, on the contrary, its results are more accurate showing up to the origin of each of the extensions to be queried.

Follow the next link to access the web

If you have any questions, leave them in the comments, we will answer you as soon as possible, and it will surely be of great help to more members of the community. Thank you! 😉

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