Compare and sync folders

Compare two folders item by item, see what differs, then copy the changes one way or both ways. Nothing changes until you click Sync and confirm.

Beta. Compare Folders is new in FileOctopus 1.0.8 and is still a beta. Click Beta at the right of its title bar and choose Send Feedback… or Discuss on Discord to tell us what works and what doesn’t. Read current limits before you sync folders that matter.

Open Compare Folders

The Compare Folders window opens and starts comparing right away. Reading the folders never changes them. Each folder has a Choose… button to pick another one. The commands have no default keys; you can give them one in Settings ▸ Keyboard.

Read the window

The two folders are named everywhere in the window, at the top and in every list and button. Between them, the direction control has three choices: → (from the first folder to the second), ← and ⇄ (Both Ways). The window opens on →. Swap exchanges the two folders. The line under the direction says in words what a sync does, for example Copy new and newer items from “Photos” to “Backup”.

Options shows a one-line summary while closed, such as Size and date · hidden files off. Open it to change how the folders are compared; a change applies at once and compares again.

• Compare contents reads files of the same size to find different contents. It is slower. Without it, files count as the same when their size matches and their dates are less than 2 seconds apart.
• Show hidden files includes hidden items. Finder’s own files (.DS_Store and folder icons) are always left out.
• Look inside packages compares the contents of packages such as apps, instead of treating each as one item.
• Names to ignore takes simple patterns, such as *.tmp, node_modules. A matching folder is left out whole.

The status line says how many differences were found and what was compared, for example 12 differences (by size and date). When nothing differs the window says These folders match. Compare Again reads both folders again; Stop (⌘.) ends a compare in progress.

Filter the rows

The bar above the list shows one kind of row at a time, each with its count: All Differences (the default), Only in “Name” for each folder, Newer, Different (same date, different size or contents), Can’t Sync and All Items. A filter with nothing in it is hidden. Filters only change what you see, never what a sync does.

Choose what each row does

Each row shows the item in both folders and, in the Action column, a chip that says what a sync will do with it. The arrow on the chip points at the folder that changes.

Click a chip to change its row: the menu lists Don’t Sync and each change the row allows, naming the folder, for example Copy to “Backup” or Replace in “Photos”. A folder that is in both places shows how many changes are inside it; its menu offers Sync Changes Inside or Don’t Sync.

In Both Ways, items missing on either side are copied, but a newer item never replaces the other one until you choose it on its row, because both sides may hold an edit.

Mirror

With → or ←, a checkbox above the totals offers Mirror, for example Move items not in “Photos” to the Trash from “Backup”. With it on, the target folder is made to match the source: items that are only in the target go to the Trash, never deleted. Mirror isn’t offered for Both Ways. Before anything goes to the Trash, FileOctopus asks a separate question, such as Move 3 items in “Backup” to the Trash?, and its button is Move to Trash.

Sync

At the bottom, the totals chips say what a sync will do, for example Copy 21 · 6.2 GB, Replace 2 and Trash 3. Click a chip to show only those rows; click it again to show all rows. The button beside them names the count, such as Sync 26 Items….

1. Click Sync N Items…. It never syncs by itself: a confirmation lists what will happen, for example Sync 26 items to “Backup”? with one line per kind of change. Return doesn’t start a sync from the window.
2. When the sync replaces items, the confirmation says Replaced items can’t be put back. and Return chooses Cancel. Click Sync to go ahead.
3. If Mirror moves items to the Trash, you’re asked again before that.

The sync runs in the same queue and progress panel as other copies and moves. Each item is checked again just before it changes: one that changed since the compare is skipped, and the summary lists it. When the sync ends, a summary says what was synced and what wasn’t, and the folders are compared again. A sync can’t be undone with Edit → Undo; items moved to the Trash can be put back from the Trash.

Escape closes the window. During a sync, stop it first with ⌘..

Free and PRO. Compare Folders needs the trial or PRO. On Free, its commands explain that it is part of FileOctopus PRO, and no folder is read. See Free and PRO.

Current limits

• Dates that differ by exactly one hour aren’t handled yet. On FAT and exFAT drives (many USB sticks and SD cards) this happens after a daylight-saving or time-zone change, and the files show as Newer although they are the same. Check such rows, or turn on Compare contents, before you sync.
• Replace can’t be undone, and no sync can be undone with Undo. Only items moved to the Trash by Mirror can be put back.
• Sync never downloads files that are only in the cloud. They show Not Downloaded and can’t be synced; download them first.
• Items that FileOctopus can’t tell apart on a disk, such as two names that differ only in capitals on a disk that ignores case, show Can’t Sync.
• A package (such as an app) that differs in the two folders isn’t replaced whole. Turn on Look inside packages to sync what is inside it.

See also feature status and current limits.