FastDMG1.0.3

FastDMG mounts disk images from the Finder without relying on Apple’s standard DiskImageMounter application. It serves as an alternative to that system utility, opening images quickly while skipping disk-image verification and automatically accepting end-user license agreements. The program supports every image type that DiskImageMounter handles, including DMG, ISO, and Toast files.

It can mount several images concurrently through multithreading, making batches of disk images practical to open. FastDMG runs in the background, does not appear in the Dock, and presents neither windows nor menus during normal use. Its native Objective-C and Cocoa implementation is a small wrapper around macOS’s hdiutil command-line tool, which indirectly uses Apple’s private DiskImages framework, while Finder document icons retain their usual appearance.

To assign it as Finder’s default image handler, place FastDMG.app in Applications, Control-click it and choose Open to bypass Gatekeeper, then select a DMG file and press Command-I. Choose FastDMG in the Open with section and click Change All; Finder will then use it whenever DMG files are opened.

FastDMG is freeware for macOS 10.13 and later, with support for both Intel and Apple Silicon Macs. Current version 1.0.3 adds a new application icon, a Universal ARM/Intel 64-bit build, Apple Developer ID signing and notarization, and support for Mojave Dark Mode.