iBored is not a pure hex editor but rather a disk block editor, which also can be used to edit files in hex. Simply drag a file into iBored's "Disks" window and then double click it to edit the file as if it was a disk of sectors. Not idea, but sometimes that's what you want, e.g. if you want to edit a disk image file.
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iBored doesn't cost anything.
Pro Supports HFS, FAT, APFS and more disk structures
Uses an extensible templates system to view structures of common disk and volume formats.
Pro Disk editor
iBored is one of the few disk editors on the Mac.
Pro Remote operation
Can be used to remotely assist in viewing and repairing disks over the internet: iBored has to be started on both computers, and then one can connect to the other and view and modify its data (after getting permissions from the target side).