What is the default image viewer on macOS?

The default image viewer on macOS is Preview. It is Apple’s built-in application for opening images and PDF documents, so double-clicking many common image files launches Preview unless the default application has been changed.

Preview began as part of NeXTSTEP, the operating system developed by NeXT, the company Steve Jobs founded before returning to Apple. Apple carried it into Mac OS X, where it became a standard utility rather than a full photo-management library. Besides viewing JPEG, PNG, GIF, TIFF, and other formats, Preview can crop, rotate, resize, annotate, sign, combine, and export documents.

A common mix-up is Quick Look, which also previews images on a Mac. Quick Look is a Finder feature activated with the Space bar; it is not the main image-viewing application. Photos, by contrast, is designed primarily for organizing and syncing a personal photo library. Preview is also the default PDF viewer on macOS, making it one of the system’s most frequently used document tools.