macOS Disk Image — Apple disk image used to distribute macOS software.
Quick facts
What is .dmg
A .dmg file is a macOS Disk Image — Apple disk image used to distribute macOS software.
In the mime-db registry it maps to application/octet-stream, and it is marked as compressible. When serving .dmg over HTTP, set the Content-Type header as shown in Developer info below.
Related entities: it maps to application/octet-stream — and is delivered over HTTP via the Content-Type header.
How to open .dmg files
Developer info
When served over HTTP, responses should set the following header:
Content-Type: application/octet-stream
Common software that reads/writes .dmg:
Relation chain
Related extensions
Related MIME types
Common uses
How to edit .dmg files
How to create .dmg files
Frequently asked questions
Common options include macOS, 7-Zip. You can also open many of these files with built-in viewers or a browser.
Create a new file in any text editor or the app that owns the format and save it with the .dmg extension.
application/octet-stream is the media type identifier used for .dmg files during network transfer (for example in the HTTP Content-Type header).
Sources & standards
Updated 2026-08-18
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