.DAT File Extension Reference
DAT is a generic file extension assigned to files that store arbitrary data created by a specific application. It can contain plain text, binary database records, video streams, or Microsoft Outlook winmail.dat attachments.
Quick Specification & Metadata
.DAT
System & Executables
application/octet-stream
Open Standard Working Group
N/A
Open Standard
Binary Header Data
1 KB – 50 MB
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What is a .DAT File? (Technical Definition & Architecture)
DAT is a generic file extension assigned to files that store arbitrary data created by a specific application. It can contain plain text, binary database records, video streams, or Microsoft Outlook winmail.dat attachments.
Formatted byte alignment adhering to international format specifications.
Adheres to formal schema and protocol documentation.
Parsed and executed identically across Windows, macOS, and Linux kernels.
DAT Binary Structure & Header Specifications
The .DAT format organizes data into validated sequential or hierarchical byte structures. Inspecting the header offset reveals the magic byte sequence Varies by application signature.
- File Signature (Magic Bytes): Varies by application signature
- MIME Content-Type: application/octet-stream
- Payload Structure: Optimized data stream with metadata headers and checksum records.
- Safety Classification: Medium Risk – Varies widely depending on source application. Inspect magic bytes before executing.
How to Open .DAT Files on Windows, Mac & Android
- 1Primary Application: Double-click or open directly with Winmail.dat Reader.
- 2Alternative Software: Open using Notepad++ / HxD Hex Editor.
- 3File Association: Right-click the file, select Open with > Choose another app, and check Always use this app.
- 1Native macOS Application: Open with Winmail.dat Reader.
- 2Quick Look Preview: Highlight the file in Finder and tap the Spacebar.
- 3Set Default App: Press Cmd + I, expand Open with, select your application, and click Change All.
- 1Compatible Mobile Apps: Download a dedicated viewer for .dat from the Google Play Store.
- 2Cloud Storage: Open through Google Drive, Dropbox, or OneDrive mobile apps.
- 3Online Browser Conversion: Use AnyFileX mobile browser tools to convert the file into universal PDF or image formats.
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.DAT MIME Types & HTTP Server Headers
When serving .dat files over HTTP or configuring REST APIs, web servers must send the official IANA registered Content-Type headers:
| MIME Type Identifier | Standard Usage | File Extensions | Copy |
|---|---|---|---|
| application/octet-stream | Standard official MIME type for .dat files | .dat |
# Nginx mime.types
types {
application/octet-stream dat;
}
# Apache .htaccess
AddType application/octet-stream .dat.DAT Magic Bytes & Hex File Signatures
In digital forensics and file signature analysis, authentic .dat files begin with a standardized magic byte sequence at byte offset 0x00 to verify file integrity and prevent extension spoofing:
Offset 0x00Varies by applDATSystem & Executables File Format.DAT vs .PDF (Detailed Format Comparison)
| Feature Metric | .DAT | Advantage | |
|---|---|---|---|
| Format Full Name | Generic Data File | Portable Document Format | Tie / Equal |
| Category | System & Executables | Documents | Tie / Equal |
| MIME Content-Type | application/octet-stream | application/pdf | Tie / Equal |
| Binary Header (Magic Bytes) | Varies by application signature | 25 50 44 46 2D (%PDF-) | Tie / Equal |
| Typical Storage Footprint | 1 KB – 50 MB | 200 KB – 25 MB | Tie / Equal |
| Universal Native Support | High / OS Standard | High / OS Standard | Tie / Equal |
.DAT Compatibility Matrix
Supported natively or through Winmail.dat Reader
Supported natively or via Notepad++ / HxD Hex Editor
Supported via open-source tools and command line utilities
Accessible through compatible mobile viewers or cloud previewers
Supported through dedicated mobile apps or cloud viewers
Accessible via web browser applications and Chrome extensions
Recommended Software for .DAT
Winmail.dat Reader
AnyFileX Tools
Notepad++ / HxD Hex Editor
Don Ho / Maël Hörz
Common Errors & Troubleshooting .DAT Files
Security & Malware Risk Assessment
Can a .DAT file carry viruses or malware?
Varies widely depending on source application. Inspect magic bytes before executing.
May support scripting or automation macros
Safe to inspect with AnyFileX's browser sandbox
- •Verify file extension in OS File Explorer options ('Show known file extensions').
- •Verify magic bytes (Varies by application signature) to ensure the file isn't a renamed executable.
- •Do not open .DAT attachments received unexpectedly via email or instant messenger.
Preguntas frecuentes
Respuestas claras a las preguntas más habituales.
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