A file with the .dat file extension is a generic data file that stores specific information relating to the program that created the file. Some apps that use them are CCleaner, Porteus, and Minecraft. They might even show up in your email as an attachment from a Microsoft Exchange Server.

What Is a DAT File?

In short, a DAT file contains important information for software to handle. The information contained inside a DAT file is usually either plain text or binary, although in rare cases you might encounter them as the actual data of a video file for programs like VCDGear or CyberLink PowerDirector.

Many programs create, open, and reference DAT files. They designed only for use by the application and not to be opened manually by the user. Many games, like Minecraft, use DAT files to store chunks of levels, which are loaded on the fly as a player navigates throughout the level.

How Do I Open a DAT File?

Because it’s difficult to tell whether the DAT file you’re dealing with contains text, pictures, videos, or config files for software on your computer, how you open a file will vary depending on what information it contains. Most of the time, though, DAT files are in plain text format, and you can open those with any standard text editor.

Using a Text Editor

We’re using Notepad++ for Windows as an example here, but you can open a DAT that contains text with any text editor, no matter what operating system you’re using. The process might be a bit different for opening the file, but it’s not complicated.

In Windows, right-click DAT file you want to open and then click the “Open With” command.

In the “Open With” window, choose the text editor you want to use and then click the “OK” button.

Provided the file you opened is text-based, you should be able to read the contents.

If you tried to open a file that doesn’t contain plain text, you might see a lot of “NUL” references and some obscure characters.

How-to Open Winmail.dat Files

Sometimes email servers—Microsoft Outlook in particular—can sometimes automatically convert an email into the DAT format. Sometimes if the recipient of a message created in Outlook isn’t using Outlook themselves, they’ll just get a winmail.dat file as an attachment instead of being able to view the full message. A straightforward way to open the file, without getting your contact to resend the email in HTML format, is to use Winmaildat.com.

After downloading the DAT file from your email, head over to Winmaildat.com and click the “Choose File” button. Locate the DAT file and then click “Open.”

After the file gets uploaded, click “Start” and the website will analyze the file.

The Result page shows everything the DAT file contains. Clicking an item downloads it to your computer, where you can open it to view its contents.


Keep in mind that because most DAT files are used within specific programs to store program settings, they probably aren’t meant to be opened manually. This means you won’t be able to read any of the data that’s contained inside the file using a normal text editor. And even if you can read the data, there’s usually not much you can do with it anyway.