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CSO file: what it is and how to open it

Compressed CD image. Here is what a .cso file contains, how to open one on any device, and a viewer that opens it right in your browser.

Open a .cso file hereChoose fileRead in your browser. Nothing is uploaded.

What the viewer shows

  • Whether the file matches the .cso signature
  • The first bytes as hex
  • A preview when your browser can display it

What is a .cso file?

A .cso file is a compressed CD image. Its registered MIME type is application/x-compressed-iso, which places it in the application or document family of formats.

CSO is a binary format: the contents are not readable text, so opening it in a text editor shows scrambled characters.

CSO file format details

Extension.cso
FormatCompressed CD image
MIME typeapplication/x-compressed-iso
CategoryApplication or document
Text or binaryBinary
File signatureNone fixed
Registered with IANANo
Other extensionsNone

How to open CSO files

WindowsWindows opens ZIP files itself. For other archive types, the free 7-Zip program opens most of them, CSO included.
MacArchive Utility opens ZIP and several other formats with a double click. The free app The Unarchiver handles many more.
iPhone and iPadThe Files app can open ZIP archives. Other archive types need an app from the App Store.
AndroidFiles by Google opens ZIP archives. Other types need an archive app such as RAR or ZArchiver.

Can you convert a .cso file?

TapToConvert does not convert CSO files. The usual route is to open the file in the program that made it and use its Export or Save as option.

CSO file FAQ

What is a .cso file?

A .cso file is a compressed CD image, with the MIME type application/x-compressed-iso.

How do I open a .cso file?

7-Zip on Windows and The Unarchiver on Mac open most archive formats.

Is a .cso file safe to open?

CSO files hold data rather than programs, but any file from an unknown source can be crafted to exploit the software that opens it. Keep that software up to date. The viewer on this page only reads the bytes and never runs anything.

What is the MIME type of .cso?

application/x-compressed-iso. Web servers send this type so browsers know how to handle the file.

Is CSO a text or binary format?

Binary. Its contents are not readable as text.

File type facts come from the IANA media type registry, the mime-db project and the freedesktop.org shared MIME database.

Similar file types

Try MP4 to MP3, HEIC, merge PDF or compress video.