CMX Image — A .cmx file is a CMX Image. It is a raster or vector image format used for photos, web assets and design work.
Quick facts
What is .cmx
A .cmx file is a CMX Image. It is a raster or vector image format used for photos, web assets and design work.
In the mime-db registry it maps to image/x-cmx. When serving .cmx over HTTP, set the Content-Type header as shown in Developer info below.
Related entities: it maps to image/x-cmx — and is delivered over HTTP via the Content-Type header.
How to open .cmx files
Developer info
When served over HTTP, responses should set the following header:
Content-Type: image/x-cmx
Common software that reads/writes .cmx:
Relation chain
Related extensions
Related MIME types
Common uses
How to edit .cmx files
How to create .cmx files
Frequently asked questions
Common options include Photoshop, GIMP, Paint. 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 .cmx extension.
image/x-cmx is the media type identifier used for .cmx files during network transfer (for example in the HTTP Content-Type header).
Sources & standards
Updated 2026-08-18
Explore this reference