How to Open an Unknown File Format?

Sometimes we receive files with unknown formats. There are many tools and techniques to identify and open these unknown files.

Steps to Open Unknown File Formats

Step	Details
1. Check the File Extension	Look at the file extension (e.g., .xyz, .abc). If the extension is missing, you can try renaming the file with the most likely extension based on context.
2. Use File Identifier Websites	Upload the file to sites like filext.com, fileinfo.com or checkfiletype.com to identify its type.
3. Try Opening with a Text Editor	Open the file in Notepad (Windows) or TextEdit (Mac). Sometimes the first few lines contain metadata or readable information that hints at the file type.
4. Use Universal File Viewers	Tools like File Viewer Plus, Free Opener or Universal Viewer support hundreds of file types. They can often open unknown or rare formats.
5. Use Online Conversion Tools	If you suspect it is a media or document file then convert it using websites like CloudConvert, Zamzar, or Convertio.
6. Check for Malware	Unknown files may be malicious. Always scan the file using antivirus software or services like VirusTotal.
7. Search by Extension	Simply Google the file extension (e.g., “how to open .abc file”).

Common Tools to Open Unknown Files

Tool Name	Purpose
File Viewer Plus	Opens 400+ formats including documents, images, audio and more.
Universal Viewer	Lightweight tool that supports text, image, binary and multimedia files.
TrID File Identifier	Identifies file types based on binary signatures not just extensions.
VLC Media Player	Can open many video/audio formats even with unknown extensions.
7-Zip / WinRAR	Sometimes unknown files are compressed archives. These tools can extract them.

Tip	Reason
Never open from untrusted sources	Unknown files can carry malware or viruses.
Use a virtual machine	Test suspicious files in a controlled and isolated environment.
Backup before testing	Always save a copy before experimenting with file conversion or renaming.

File Type	Solution
file.xyz	Could be a 3D file or plain text. Try with Notepad or Blender.
file.dat	Generic data file open with a hex editor or use the originating app.
file.part	A partially downloaded file. Resume or complete the download.
file.tmp	Temporary file usually safe to delete if not in use.