Dissecting Apple's Sparse Image Format (ASIF)

Apple announced a new sparse disk image format called ASIF (Apple Sparse Image Format) for macOS 26 Tahoe, designed for use with virtual machines and similar to existing formats like VMDK and QCOW2. A developer reverse-engineered the ASIF file format by creating test files, analyzing hexdumps, and methodically identifying header structures and integer fields to understand how the format stores large disks efficiently in a sparse manner.