How To Open A File Without An Extension

When you encounter a file without an extension you likely downloaded it from the internet, or someone shared it with you. At this point, you probably won’t be able to open the file to see its contents.

This is because a file extension or a file association, is compulsory so an application or a program can be assigned to perform the task.

This article discusses the importance of a file extension and why it is required, how you can view it, and how can you open an unknown file type or a file without an extension.

What is a file extension?

A file extension is a series of alphabets followed by a period at the end of a file name. For example, if there is a text file named “SampleFile”, its full name with the file extension could be “SampleFile.txt”, “SampleFile.docx”, etc.

The purpose of a file extension is for the operating system to know which app or program to use when opening or running the file. The file extension, or the file type, is associated with a supported program. This is why a “.DOCX” file may open with Microsoft Word by default.

However, if you try opening an unknown file with no file extension, the chances are that you will see the “Open with” dialog box on a Windows computer. From here, you can select which app to use to open the file. There is likely no preinstalled app that can handle the file type, and you may have to download/install one.

It is at this point you must know which application to download or install so that you have the correct one, which also supports the file type. Hence, we must know the file extension of the unknown file.

Before continuing to learn how to know the file extension of the unknown file type, let’s first see how to view file extensions in Windows.

How to show hidden file extensions in Windows

By default, all Windows operating systems are programmed to hide the file extension. Since the file extension isn’t displaying, users may think that all files do not have a file extension. Therefore, make sure that you can see the file extensions by enabling this Windows feature.

Note that if a file is still missing an extension even after you have configured them to show, then it is likely that the particular file does not have one.

Show file extension in Windows 10

Use the following steps to show all file extensions on a Windows 10 computer:

1. Press the Windows Key + E to open the File Explorer.

2. Click View from the ribbon menu.

3. Check the box with “File name extensions.”

   

Now, all files should show the file extension.

Show file extension in Windows 11

Use the following steps to show all file extensions on a Windows 11 computer:

1. Press the Windows Key + E to open the File Explorer.

2. Click View from the ribbon menu and expand it.

3. Click Show to expand it.

4. Click “File name extensions” to show the file extensions.

   

Alternative method to show file extensions in Windows

Another way to show file extensions is through the File Explorer’s Options menu. You can use the following steps on either Windows 10 or 11 to show file extensions:

1. Press the Windows Key + E to open the File Explorer.

2. Click on the 3 dots in the ribbon menu and then click Options.

   Note: In Windows 10, click the View button in the ribbon menu and click Options.

   

3. Switch to the View tab.

4. Under the “Advanced settings” section, unselect “Hide extensions for known file types.”

   

5. Click Apply and Ok.

These are the methods to view all file extensions in Windows. However, if you still find a file with no extension showing, likely, there isn’t one assigned. Regardless, below are the methods to open a file without an extension.

Opening an unknown file without an extension

The best method to open an unknown file is to find out what the file extension is, so you can assign it manually and then the OS will automatically open it using the default app. However, even if you open an unknown file’s properties, you won’t find any details about the type of file. Instead, you will find only “File” written, as in the image below:

Toolsley File Identifier

Toolsley is a vendor that provides different kinds of troubleshooting tools. The “File Identifier” is one of those tools.

The Toolsley File Identifier is an online tool that can detect what kind of a file it is, even without its extension. All you have to do is upload the file and it will tell you the file type. Since your computer handles the detecting work using the website’s JavaScript, you also do not have to worry about the size of the file you upload.

1. Open Toolsley File Identifier using any web browser.

2. Click “Select a file” and then upload the unknown file.

3. You will then immediately see the file type in the browser.

   

TrID Online

TrID Online is another online tool that can detect a file type by cross-matching its contents with others. It then tells you the percentage similarities with other file types. Using that information, you can define your file’s extension and open it with an app or program.

Note: TrID also has a command-line and GUI-based version, but using the online tool gets the job done just as easily.

Use the following steps to identify a file type using TrID Online:

1. Open TrID Online using any web browser.

2. Click “Choose file” and then select the unknown file.

3. Click Start.

   

The online tool will now display all the file types and the percentages which match the file format of the uploaded unknown file.

You can now use this information and assign the most-matching file extension to the unknown file yourself.

Digital Record Object Identification (DROID)

DROID is a tool that you can run on your computer to identify single or multiple unknown file types at once. Here are the steps to use it:

1. Open the DROID website and download the current version.

2. Right-click the downloaded compressed file and extract the contents.

3. Navigate to the extracted folder and double-click the “droid.bat” file.

4. On the Defender SmartScreen prompt, click “More info” and then click “Run anyway.”

   

   The DROID app will now launch. Note that it may take some time.

5. Now drag and drop the unknown file into the DROID app.

   

6. Click Start from the ribbon menu.

   The DROID app will now show the file format in the “Format” column.

   

Other third-party tools

There are many similar online and downloadable tools and utilities that you can use to determine the file type and format for a file without an extension. Some we have discussed already, while some others can also be used, like these:

• FILExt Online File Viewer
• File Magic – Universal File Viewer

Once you have found out what type or format a file has, you can then continue to assign it a file type by renaming it.

How to set file extension by renaming

By assigning a file extension to the unknown file type, you automatically tell the OS which app or apps to use to open it. The simplest way of doing so is by renaming the file while you have configured all file extensions to show (as discussed above).

Once you have the extensions visible, you can begin amending the file type by simply inserting the extension determined using one of the tools above. For instance, if you found that the unknown file is a JPEG, simply insert “.jpeg” at the end of its name.

Here are the steps to manually configure a file extension:

1. Right-click on the unknown file and then click Rename from the context menu.

2. At the end of the file name, insert a period (dot), followed by the file extension.

   

3. Press Enter.

After assigning the correct file extension, you will notice that the file’s icon also changes. This confirms that the file type has been assigned. You can now continue to open the file type using the associated app.

Ending Thoughts

If a file does not have a file extension, it does not necessarily mean that it is useless. You can determine the actual file type using tools, assign the file extension manually, and then open it using the associated application.

This article lists multiple tools that can be used to find out the file type so you can assign an appropriate extension.