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What is an Application Octet Stream File?

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The Octet Stream files are the binary version of MIME-type. They are able to be any file format such as a .jpeg or an .exe renamed during transmission from source to destination. For your information, the Octet streams are known as byte streams.


You have to know that the Octet-Stream file is used for file attachments on the Web with an unknown file type. These Octet-Stream files are arbitrary binary data files that are able to be in any multimedia format. Based on the research, the Octet-Stream was promoted for Web browsers to know which the file attachment is in an unknown file type. Aside from that, it also allows you to choose to download and save the attached file in any file format which you want. In other cases, the Octet-Stream file format is used to declare the attached file which is able to be saved in a recommended file format.

What is an Application Octet Stream File1

We get information that an Octet-Stream file is able to be opened by renaming the extension of the attached file to a specific file extension, and then by using an application with support for opening such files. For instance, an Octet-Stream file is able to  be renamed to a .txt file and then Notepad can be used to open the file. So, you will need to know the file type of the attached Octet-Stream file before you are able to rename the file in the correct file extension.

As we said before that an Octet Stream is the binary version of a MIME-type file. Some of you may not know regarding MIME. Well, now we are going to explain it. MIME is the identifier for file formats. The IANA (Internet Assigned Numbers Authority) is the official authority for the standardization and publication of those classifications. They are used to denote the type of email message content and attachments. Also, Media types are used by other internet protocols such as HTTP and document file formats (HTML) for similar purposes.

According to the research, an octet is an eight-bit byte. Browsers and email clients rename files with missing the extensions to octet stream regularly. If you get a problem when you try to open an octet-stream file, you are able to try renaming the file extension if the file type is displayed once you are downloading an attachment. While if the file type is unknown and cannot be determined, you are able to ask the sender about the file type before you try to rename the file. After an extension is renamed properly, now the file will open easily. Another way is to open the appropriate program for the file type and then attempt to open the file in the program with no rename of the extension. In this way, you need to ensure to open the file in the appropriate application based on the file type. Normally, the Octet-Stream files are executable application files. If you still get a problem when you are opening a file, you have to request the sender try to retransmit the file. Usually, Web Clients and Email are rare opening the Octet Stream files, however they may be able to determine the appropriate program to open the file.


Once you try to download an unknown file from the Web, your computer may recognize it as an Octet-Stream file. As we know that an Octet-stream does not refer to a specific type of file. It is able to be anything from a spreadsheet to an executable program. By the way, how to open an unidentified file? To open an unidentified file, you need to figure out which program can open the file as a document or change the extension file to run as a program.

Files With Extensions

  • Firstly, you have to double-click the octet-stream file after downloading it. If the file contains a usable extension, it is able to load properly even if your Web browser cannot identify it. Besides, Windows is going to show a list of programs to use.
  • After that, you are able to click a program in the list to load the file by using the selected software. If you do not see any options in the list, you have to click at “More Options.” For selecting a specific program not found on either list, simply you are able to click at Look for Another App on This PC.
  • The next step, you have to check whether the file loads correctly or not. If it does not, you need to quit the program and try again with another application.
  • Lastly, you are able to double-click the file again, when you discover a working application. Next, you have to check the box to select at ‘Use this app’ for all similar files and then take the correct program.

Files Without Extensions

  • Firstly, you have to double-click the file to show a list of programs on your computer. In this step, you are able to pick one to try loading the file. If the file does not load correctly, you have to quit the program and try another.
  • The second step, you are able to select the file after figuring out its type. Simply, press “F2” for renaming the file and type its extension after the file name. For instance, if you discover a file to be a Word 2013 document, you are able to add “.docx” without quotes. Then, simply press Enter. The typed extension is going to disappear but the icon of the file can change, recognizing its new type.
  • The last step, you have to append the extension “.exe” if you need to run a file as an application, rather than as a document in another program. Files that appear as octet-stream files are applications, but you only need to run a downloaded application if you trust its source.

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