BLIT
Big files, moved fast, proven intact.
A native Mac app for moving large files between SFTP servers, external drives and NAS shares. Every file is checked by SHA-256 where it lands, before it gets its real name.
Item
Throughput · 60 s
Link data
Log
Warning
Verified, not assumed
Hashed on the server
Blit asks the server for each file's SHA-256 while the file is still in its cache, and hashes its own copy as the bytes arrive. The two have to match before the file gets its real name.
Until then it's a .blitpart. A half-written file never sits under a real name.
Hashed on the NAS
Copies to a Synology share are checked by sha256sum on the NAS itself, over SSH, so a copy can't pass by coming back from the Mac's own cache.
94% of a 1 GbE link's line rate, every file verified on the NAS.
Never quietly downgraded
An interrupted hash is never accepted as "size looks right". Size-only checks are labelled everywhere they appear, and a move deletes a source only after its copy's hash has matched.
Proof you can look up
Every file lands in the Transfer Log: size, hash, how it was verified, and when. Search it by name or SHA-256, and export it as CSV.
Fast across an ocean
Tuned for a server 148 ms away, where one stock SFTP connection crawls. Parallel connections, pipelined reads, and a receive buffer bigger than macOS allows by default: 22.5 TB a month in about 4.7 days instead of 24.5.
Measured from the Mac to a server 148 ms away, same server and network for every method.
Resumes anything
Each part file records which byte ranges are on disk. Quit, sleep, lose Wi-Fi, unplug the drive: the queue survives and picks up mid-file.
A queue you steer
Pause, resume, reorder, cancel, Retry Now. Downloads and drive-to-NAS copies run in separate lanes, and a full disk waits for space instead of failing.
Says why it's slow
The HUD shows the round trip, the route (and warns when Wi-Fi carries it while a cable is plugged in), and says when the server's disk, not the network, is the limit.
The HUD
Everything else in Blit is a plain Mac app. Status and motion get a 1-bit, pixel-terminal instrument, inspired by 1-bit pixel art and the Nostromo's screens: black and grey, with muted red reserved for failures. Every state has a glyph or a word, never color alone.
A real Mac app
Finder-style browser
Servers, drives and NAS shares in one sidebar. Newest first, Quick Look, Get Info, undo, favorites, and two panes to drag between.
Rename N items
Replace, add or format names in bulk, with a live preview, multi-step rules and presets for your naming conventions.
Copy to / Move to
Send reviewed files to a NAS folder without dragging. A move removes each file only once its copy is verified.
Menu bar and Dock
Progress, rate and queue totals with the window closed, a pixel Dock badge, and the Mac kept awake while it works.
Spec sheet
| Platform | macOS 27, Apple silicon. SwiftUI and AppKit, following the Human Interface Guidelines. |
| Transport | SwiftNIO SSH with Blit's own pipelined SFTP v3 client. Password or ed25519 / ECDSA keys, stored in the Keychain. |
| Verification | SHA-256 on the server (with a hash cache), on the NAS, or by read-back, labelled by strength. |
| Resume | Byte-range state beside each part file, a durable queue, and retries with backoff. |
| Trust | Host keys pinned, known_hosts honoured (hashed entries too), and a changed key refused. |
| Distribution | Sold directly, one-time, through Lemon Squeezy. Builds are signed with Developer ID and notarized by Apple. |
Price
- 7-day free trial, everything included
- 30-day refunds, no questions asked
- Updates to Blit 1.x included
- After the trial, transfers already queued still finish