Kayabyte

Help: Pairfold

Last updated: 13 November 2026

Setup and common questions. If something here doesn’t solve it, email support@kayabyte.dev with your Pairfold and macOS versions and, if a run went wrong, the log (open the pair, History, Export Log). Please don’t send us your files. See also support and the guides.

Contents

Set up your first pair

  1. Click New Pair. Choose the first folder, then the second. A pair is two folders, for example a project folder on your Mac and a folder on an external drive.
  2. Give it a name if you like (optional).
  3. Choose Mirror or Two-way.
  4. Click Check and Preview, read the list, then click Sync.

Pairfold remembers your choice of folders, also after a restart. If a saved folder can no longer be opened, the pair shows Choose Again: one click and a folder panel.

Mirror or two-way

Mirror: the second folder is made to match the first. The first folder is never changed. Files that are new or changed in the first are copied; files that are gone from the first, or replaced, are moved from the second to the archive. Use it for backups.

Two-way: new and changed files go in both directions. Pairfold remembers the state after the last clean sync, so it can tell a file that was deleted on one side from a file that was never there. A file deleted on one side and unchanged on the other is removed on the other side (moved to the archive). A file deleted on one side and changed on the other is kept and restored. When both sides changed the same file, or both made a new file with the same name, it is a conflict: by default it is left alone for you to decide, and in the pair’s settings you can let the newer one win, with the older one going to the archive. Use two-way for a folder you work in on two places.

See two-way sync between a Mac and an external drive and mirror without deleting files.

The preview

Check and Preview compares both folders and lists every change grouped as New, Changed, To archive and Conflicts, with sizes. Untick what you want left alone. Nothing changes until you click Sync, and Sync runs exactly that list. A file that changed after the preview is skipped and reported, not copied half-way. The list also shows items Pairfold will not touch and why: changed since the preview, only in iCloud, too large for FAT32, a name the disk cannot store, or a conflict you did not decide.

If a run would replace or archive a large share of the files, the preview asks you to confirm. A scheduled run never goes ahead in that case: you get a notification.

The archive folder

Every replaced or removed file is moved, not deleted, to a dated folder, one per run. By default it is a hidden folder named .pairfold-archive on each disk. In the pair’s settings you can choose another archive folder and set it to be emptied after 30 days, 90 days or a year, or never. History has a button to show the archive in Finder. The archive is a plain folder, not a version browser, and the archive folder cannot be inside a synced folder.

Schedules and runs when a drive connects

In the pair’s settings choose how often it runs (an interval, or once a day) or tick Run when a disk or share is connected. Both only run while Pairfold is open, which can be in the menu bar with the window closed. A run is skipped when another run of that pair is still going or when the pair needs attention. The sidebar shows Checked with the time of the last check, also when nothing needed doing.

Open at login

In Pairfold’s settings, turn on Open Pairfold at login so schedules keep running after a restart. It is off until you turn it on. macOS shows a “Login Item Added” notice. You can switch it off in Pairfold or in System Settings, General, Login Items. If macOS has switched it off, Pairfold says so.

External drives and NAS

APFS, Mac OS Extended, exFAT and FAT32 drives work, and so do network shares you have mounted in Finder (Go, Connect to Server): choose a folder on the share when you make the pair. Pairfold does not sign in to a NAS or use FTP or SFTP itself. FAT32 cannot hold files over 4 GB, and some names are not allowed on FAT: those items are listed as left alone. If every run copies files again on an exFAT or FAT32 drive, see why files copy again. We tested copying to an SMB share in a virtual machine; choosing a folder on a share in the app’s file panel on a real NAS is not something we tested, so try a small folder first.

Files that are only in iCloud

A file in iCloud Drive that is not downloaded to the Mac is shown as left alone (“in iCloud only”). Pairfold does not download such files in bulk, never copies an empty stand-in, and does not count them as missing. To include one, download it in Finder first.

When a disk is missing

Before every run Pairfold checks that both folders are the ones you chose. If a drive is not connected, or a different disk is at the same place, the run stops with “disk not connected” or “a different disk is at the folder’s place”. Nothing is copied or archived. Connect the drive or mount the share and click Check Again. If you really replaced the folder or the disk, choose Use This Folder or Choose Again. If the drive is pulled during a run, the file being copied is not put in place and the old one stays. The next run cleans up and continues.

Questions

Does Pairfold delete files? No file is deleted outright. A replaced or removed file goes to the archive folder.

Can I sync more than two folders? Make one pair for each two folders. Pairfold works with pairs.

How do I see what a run did? Open the pair, History: copied, archived and left-alone counts for each run, and a plain log you can export.

Does it need an account or the internet? No account. It reads and writes only the folders you choose. The App Store version has no network access of its own; the download from this site goes online only to check your licence and for updates. See the privacy policy.

What does the free download do? The download keeps one folder pair: preview and sync by hand, with every safety feature. A licence (USD 12.99 once, 2 Macs, one year of updates) adds more pairs, schedules and runs when a disk is connected. Enter the key under Pairfold, Enter Licence Key. If you remove the licence, extra pairs stay saved but only the first one runs.

Does it work on macOS 15? Pairfold needs macOS 26 or later.

Where do I get it? On the Pairfold page.

Something went wrong. What do I send? Your macOS and Pairfold versions and the exported log, to support@kayabyte.dev.