FolderSync
One-way sync that keeps the old copy of every file it overwrote.
Free right now — no account, no card
Preview
1 interface design, then a screenshot of it running. Drag, scroll or use the arrows.
Free while we’re in preview
Get FolderSync
One-way sync that keeps the old copy of every file it overwrote.
The Mac button is for Apple Silicon. On an older Intel Mac, get this one instead.
One file, both ways. Double-click it for the window. Run the same file from a command prompt with arguments and it behaves as the command-line tool, because the engine is inside it. Nothing else to download and nothing to keep beside it.
Early preview. The window has been built and run, but not yet on a real Windows PC or Mac, so expect rough edges. The engine underneath it is fully tested.
- One file — no installer
- Runs on your machine, offline
- Source code published below
Free while in preview. It isn’t signed yet, so Windows or macOS will ask you to confirm the first time you open it. At launch, FolderSync is included in every plan along with the rest of the range.
The sync you regret
You mirror a folder and something in the source turns out to have been wrong. Under a plain mirror the destination’s old content is simply gone. FolderSync archives a file’s existing content into a versions directory before overwriting it, and before removing it under --delete. A bad sync becomes undoable rather than just diagnosable.
Getting something back
foldersync versions reports/q3.xlsx --versions ./v lists every archived copy of that path, newest first. restore brings one back, either the latest or an exact timestamp.
Restoring is itself versioned. Whatever currently sits at that path is archived before the older copy lands on it, so pulling back last week’s version never quietly destroys this week’s work.
Only an existing destination file being overwritten or deleted triggers a snapshot. A new file has no prior content, so nothing is archived for it. Changes are detected by size plus SHA-256, not timestamps. Two-way sync isn’t here.
Reading on the job itself
- How to keep two folders in sync without losing anything Decide first whether one side is authoritative. If it is, mirror one way and think hard before enabling del...
Advanced & technical details Command-line builds, source code, checksums and a recorded session — for developers and IT teams
A working CLI prototype of the versioned-sync engine: every file a sync would overwrite or delete is preserved in a version history first, with list/restore and a recursive safety guarantee (a restore versions what it overwrites too). Two-way sync with conflict resolution and cloud/NAS targets are still on the roadmap.
Naming status
Working name only — brand verdict **AVOID** (Very High). Collision: FolderSync. Rename completely.
What it draws on
Existing paid software whose best ideas shaped this program: GoodSync, Syncovery, SyncBackPro, ViceVersa Pro.
Command line
There is nothing extra to install. The program you download is the command-line tool as well: give it arguments instead of double-clicking it and it runs as one, with its output on your terminal. The standalone builds below are the same engine on its own, for machines where you would rather not ship a window at all.
FolderSync - versioned one-way folder sync with undo history
Usage:
foldersync sync <src> <dst> --versions <versionsdir> [--delete] [--apply]
foldersync versions <dst-relative-path> --versions <versionsdir> [--json]
foldersync restore <dst-relative-path> <dst-root> --versions <versionsdir> [--at <timestamp-or-latest>] [--apply]
foldersync help
Run "foldersync <command> -h" for details on a specific command.
FolderSync never overwrites or deletes an existing destination file
without first archiving its current content into the version history
directory, so any sync can be undone with "restore".Recorded from the shipped binary, not written by hand.
Source
Every file the program is built from:
console.go · console_test.go · guided.go · main.go
SHA-256 checksums · build instructions & scope notes · full build plan