SuperDuper is a Mac disk cloning/backup utility from Shirt Pocket Software (Dave Nanian), designed to copy your startup drive (or other disk volume) for quick recovery in the event of disk failure or software problems. Its “smart copy” feature can update a clone quickly after the first full backup, copying only the files that have changed, which is typically far faster than recopying the whole volume.
Other features include bootable clones, backup to disk images (compatible with Apple Software Restore), which offer a way to backup over a network; customization via “Copy Scripts”; logging; “sandboxing”, which shares your primary boot volume’s data files (and applications) to an experimental boot volume; options to shutdown, restart or eject after cloning; the ability to run Unix shell scripts; Time Machine compatibility; AppleScript support; APFS snapshot support and recovery volume support; scheduled backups; and the ability to store a bootable backup alongside Time Machine backups, among other capabilities.

SuperDuper 3.3.1 is priced at $27.95 for OS X 10.10 and up. (Older versions support systems as early as Mac OS X 10.2.) In trial mode, prior to purchase, SuperDuper can clone a drive but lacks Smart Copy and other features when unregistered. The latest version is “fully compatible with macOS Catalina (10.15)”, among other features.

Version 3.3 lets you ignore “missing drive” errors during scheduled copies, and also improves Smart Wake, which ensures your backups happen whether your Mac is awake or asleep… and won’t turn on your screen if your Mac is already awake. This new version also improves Smart Delete, an awesome new capability that minimizes the possibility of disk full errors while maintaining safety with no speed penalty, native Notification Center support, a Finder extension to quickly run copies, and other improvements. SuperDuper can even create and copy from snapshots, which means with an APFS backup drive, you can restore today’s Smart Update, yesterday’s, etc.