View contents of a ICO container file on macOS ICO file extension is a container file format that may include several icon images of different sizes. I'd like to know how I may access and view what is inside a ICO file, i.e. the different images it contains, and possibly any metadata.
The built-in Preview.app can handle ICO files and show the contents of the container. It can also show the file metadata. To view file metadata, use the keyboard shortcut, Command + i.



Right click on one of the images, select Export As... and select the desired format.