NTFSKit

Full read/write NTFS for macOS — the world's first pure-FSKit NTFS driver with Kernel-Offloaded I/O.

Plug in an NTFS disk and it just mounts, read/write, at device speed. No kext. No Reduced Security. No macFUSE. No terminal ceremony.

Why it's different

	NTFSKit	Paragon / Tuxera	Mounty / ntfs-3g+FUSE
Architecture	FSKit (userspace, macOS 26)	kext	macFUSE kext / FUSE-T
Reduced Security required	No	Yes (Apple Silicon)	Yes (macFUSE)
Auto-mount read/write	Yes	Yes	No (remount dance)
Write path	Kernel-Offloaded I/O — the kernel writes file data directly to disk; the driver only maps extents	kernel driver	userspace copy (~1–20 MB/s)
Survives macOS updates	By design (no kernel code)	Historically breaks	Historically breaks
Price	Free & open source (driver)	$15–30, re-paid per macOS era	Free

Measured: 572 MB/s sequential writes on a RAM-backed test volume (driver ceiling — real disks run at their own device speed, verified kernel-direct on USB hardware). ~28× faster than FUSE-T-based setups.

Features

• Automatic read/write mounting of NTFS volumes (USB, external SSD/HDD, images)
• Kernel-Offloaded I/O: blockmapFile extent mapping, allocate-without-zeroing writes (initialized_size-correct, no stale-data exposure)
• Real fsck: verifies + replays the NTFS $LogFile journal, clears dirty flag
• Format as NTFS from Disk Utility / diskutil eraseVolume NTFSKit Name diskN
• Extended attributes stored as NTFS Alternate Data Streams — no ._ files, round-trips to Windows
• Windows hibernation / Fast Startup detected → safe read-only fallback with a clear in-app explanation
• Symlinks, Unicode names, volume label read at probe (mounts as /Volumes/<YourLabel>), stable volume UUIDs from the NTFS serial

Requirements

• macOS 15.4+ (Apple Silicon)
• One-time enable: System Settings → General → Login Items & Extensions → File System Extensions → NTFSKit

Building

# 1. libntfs-3g (static) — see refs/ntfs-3g (configure && make)
# 2. Generate the Xcode project and build
xcodegen generate
xcodebuild -scheme NTFSKit -configuration Release -allowProvisioningUpdates build
# 3. Engine tests (no FSKit needed)
cd NTFSModule/bridge && clang -Wall -DTEST_FORMAT -DHAVE_CONFIG_H \
  -I../../refs/ntfs-3g -I../../refs/ntfs-3g/include -I../../refs/ntfs-3g/include/ntfs-3g \
  -Imkntfs -I. test_bridge.c ntfs_bridge.c mkntfs/*.c \
  ../../refs/ntfs-3g/libntfs-3g/.libs/libntfs-3g.a -framework CoreFoundation -o test_bridge

Architecture notes (for FSKit implementers)

Hard-won lessons, free to a good home:

• FSKit tracks items by object identity. Return one live FSItem per path or unlinks are silently deferred forever.
• The kernel buffer cache (metadataRead/Write) attaches at kernel mount — during activate it returns EIO. Start on plain read/write, upgrade on first success. Post-mount, buffer-cache I/O is what lets the engine touch metadata inside blockmapFile without deadlocking.
• KOIO is all-or-nothing per volume: advertising FSSupportsKernelOffloadedIO while inhibiting every item wedges kernel writeback (unkillable state-U writers).
• startCheck must complete its Progress and call task.didComplete asynchronously — a pre-completed Progress deadlocks fskitd and diskarbitrationd system-wide.
• Purge (metadataPurge) engine-primed buffer-cache ranges before the kernel writes those sectors directly, or later cache reads return stale data.

Licensing

• Driver (NTFSModule/, fsbundle/): GPL-2.0 — see NTFSModule/LICENSE.GPL2. Built on libntfs-3g / ntfsprogs (© their authors; commercially dual-licensed by Tuxera Inc.).
• App UI (App/): proprietary (see LICENSE). The driver is free forever; the app's Pro conveniences fund development.