What is the DAT file format?
Files with the .dat extension contain text or binary data. Because .dat is a general-purpose extension shared by many unrelated programs, such files may include data of widely varying structure, meaning, and size. The formatting of this data depends entirely on the program that created or uses the given file.
Sometimes .dat files store data that is an internal component of a program and should not be modified manually. When the content is plain text, they can be opened with any text editor; when binary, a tool such as HxD or the file command on Linux will reveal the underlying structure. .dat files occasionally follow a recognized format such as CSV - in that case, they can be imported, converted, or edited directly in a spreadsheet application.
Unlike typed formats, .dat carries no fixed file signature (magic bytes), so the extension alone tells you nothing about the actual encoding. To identify an unknown .dat file, inspect its first bytes in a hex editor or run file mydata.dat on Linux/macOS. A few well-known programs give their .dat files a specific internal structure - for example, Outlook attaches TNEF-encoded data as winmail.dat, and Minecraft stores world metadata in level.dat (an NBT-encoded binary file) - but these are effectively separate formats that happen to share the .dat extension.
The MIME type conventionally assigned to generic .dat files is application/octet-stream.
Security & safety
RISK: MEDIUMA generic .dat is opaque, so treat unexpected ones with care: malware sometimes stores its payload or configuration as .dat, and a .dat arriving from an unknown source deserves the same suspicion as any unknown download. Inspecting a .dat in a hex/text editor is safe - it does not execute the contents. Don't assume renaming makes a file safe or usable; verify the real format first. Avoid uploading potentially confidential .dat files to online "data converters"; use a local tool.
Format details
in a nutshellFULL NAMEProgram Data File (generic)
DEVELOPERN/A (generic "data" suffix shared by many programs)since 1970s-1980s (generic 'data' suffix predates DOS; used across CP/M, DOS, Unix)
CATEGORYData Files
MIME TYPEapplication/octet-stream
TYPEGeneric application data - opaque content written by a specific program (text or binary)
STANDARDOpen · royalty-free
This extension is also used by…
- Outlook winmail.dat (TNEF) - A Microsoft Outlook/Exchange TNEF wrapper (signature 0x223E9F78) that hides real e-mail attachments; extract with a TNEF tool.
- Video CD AVSEQ##.DAT - MPEG-1 video stored in a Video CD's MPEGAV folder; plays directly in VLC.
- Minecraft level.dat / Windows NTUSER.DAT - level.dat is a gzip-compressed NBT world file (NBTExplorer); NTUSER.DAT is the per-user Windows registry hive - never delete it.
Programs that open DAT files
Windows3 apps
FileAlyzer
Free Right-click → FileAlyzer to analyze headers and guess what the unknown .dat really is. 
Notepad
Open-source Open the .dat - if you see readable text it's a config/log/export; if gibberish, it's binary and needs the original app.
HxD (hex editor)
Free Inspect the first bytes to recognise the real format (e.g. 1F 8B = gzip, 50 4B = ZIP, printable ASCII = text). 
macOS1 app
TextEdit / any text editor
Built-in Open the .dat as plain text; readable means config/export, gibberish means binary data needing its source app. 
Linux1 app
file (command line)
Open-source Run 'file unknown.dat' in a terminal to identify the actual content type, then open with the matching program. Technical details
deep spec| Format type | Generic application data - content structure is entirely defined by the writing program; no universal encoding or layout |
| Content encoding | Text or binary; determined by the producing application |
| File signature (magic bytes) | None for the generic format - identification requires inspecting the file content or knowing the source application |
| MIME type | `application/octet-stream` |
| Typical use cases | Configuration storage, application cache, saved game state, export/import interchange, internal program state |
| Identification method | Run `file <filename>.dat` on Linux/macOS, use TrID or FileAlyzer on Windows, or inspect with a hex editor |
| Text variant handling | When content is plain text, any text editor (Notepad, TextEdit, nano) can open and display it |
| Binary variant handling | Binary `.dat` files require a hex editor such as HxD, or the specific application that produced them |
| Named variant: winmail.dat | TNEF (Transport Neutral Encapsulation Format) email attachment produced by Microsoft Outlook; requires a TNEF decoder to extract embedded content |
| Named variant: level.dat | Minecraft world metadata file using Named Binary Tag (NBT) encoding; stores world seed, game mode, time, and player position |
| Named variant: video.dat | MPEG-1 video stream in Video CD (VCD) sector format; playable with VCD-capable media players |
| CSV-compatible variant | Some applications write `.dat` files as plain CSV or tab-delimited text, importable directly into spreadsheet software |
| Related extensions | `.data`, `.bin`, `.db`, `.tmp` - alternative generic data suffixes used in similar contexts |
| Platform history | The `.dat` suffix has been used across CP/M, MS-DOS, Unix, and Windows since the late 1970s-1980s |
| Released | 1970s-1980s (generic 'data' suffix predates DOS; used across CP/M, DOS, Unix) |
| Open standard | Yes · royalty-free |
DAT conversions
Possible
.DAT .CSVGUIDE
Yes, when the .dat is already delimited text -- open it in Excel or LibreOffice Calc and import with the…
How to convert
.DAT .TXTGUIDE
Yes, if your DAT file contains plain text -- open it in any text editor and save as .txt, or just rename a…
How to convert
.DAT .XMLGUIDE
Yes, but only when the DAT file contains structured text -- the fastest route is a short Python script that…
How to convert
Community Q&A
asked by users
D
L
Frequently asked questions
How can I tell what program created my .dat file?
Look at the folder it's in and the sibling files (the app's name is usually nearby), then check the first bytes in a hex editor or run TrID / the Linux 'file' command to match a known signature.
I opened my .dat in Notepad and it's gibberish - now what?
That means it's binary data, not text. Find the program that created it (check the folder/app it came from) and open it there, or use FileAlyzer / 'file' to identify the real format.
Can I convert a DAT file to something usable?
Only once you know what it actually is. If it's delimited text you can import it to CSV/XLSX; if it's binary app data there's no generic converter - you must open it in the program that made it and export from there.
Can I just rename .dat to .jpg / .mp3 / .docx?
Renaming never converts data - it only works when the file already IS that format with a wrong extension. Verify the real format first (hex editor or 'file' command), then rename.
Is it safe to delete a .dat file?
It depends what wrote it. App caches are usually safe to delete and get regenerated, but a program's save or data file may be important - and system .dat files must be left alone. Identify the owner before deleting.
Why are there so many different .dat files that work differently?
Because '.dat' just means 'data' - it's a generic label many unrelated programs reused. Each app defines its own .dat layout, so there's no single way to open them all.
References
1TrID - file identifier (signature database)mark0.net
2FileAlyzer - file analysis toolwww.safer-networking.org
