Folder Comparison

Matches up the contents of the two folders open in pane A and pane B and lists where they differ. Open it from the compare button on the action bar. The comparison itself is read-only and never modifies a file — nothing is written unless you run Sync A → B from the result, described below.

• Compare by: three choices.
• Size only — the fastest
• Size and modification time (default) — usually the right choice. Modification times within 2 seconds are treated as identical, because USB drives and NAS store timestamps at a coarser resolution and a strict comparison would mark every file as different

• Contents (hash) — the most reliable, but it reads the whole file so it takes time. Only files of equal size are read, since a size difference already settles the matter

• Reading the result: the marker at the start of each row shows the state. The shapes differ, so you never have to rely on colour alone.

Marker	Meaning
=	Identical
→	Only on the left
←	Only on the right
Compare mark	On both sides but the contents differ
Case mark	Only the letter case of the name differs

• Identical items are hidden by default, because you came to look at the differences and showing everything buries them. Turn on Show identical items too to reveal them. The counts along the bottom always include them, so nothing is lost.

• An exact one-hour gap is shown separately as a likely daylight-saving artefact. It is not treated as identical, but you can see that the contents are not actually different.

• Names differing only in letter case are shown as their own state rather than silently treated as identical, since some environments handle them as two separate files.

• Exclusions: folders that tend to flood the result, such as node_modules and .git, are left out by default. Edit the list freely under Exclusions (one pattern per line; lines starting with # are comments).

• Folders that could not be read: the comparison does not stop when permissions block a folder. It does not silently report zero either — it says "N folders could not be read" so you know the result is incomplete by that much.

• Shortcuts (junctions and symbolic links) are not followed by default, since following them can count the same file twice or loop forever.

Bringing pane B into line with pane A

Once the comparison has shown you the differences, you can bring the pane B side into line with pane A without leaving the window. Use the Sync A → B button on the result.

• It is one-way. Only the pane B side changes; pane A is never modified. Two-way syncing would require deciding which side wins in every conflict, which makes the outcome impossible to predict in advance, so it is deliberately not offered.

• The breakdown is shown before you press it. Next to the button you see "N to copy / M to overwrite / K to delete", and you are asked to confirm once more before it runs. When there is nothing to do, the button cannot be pressed.

• Items that exist only on the right are not deleted by default, because deletion is the mistake the word "sync" invites most easily. To remove them, tick Delete items that exist only on the right. The delete count in the breakdown updates immediately, so you can always check the number before pressing.

• Ctrl+Z puts it back. Overwriting and deleting cannot be taken back on their own, so the original files are moved to a backup folder before the run — a single undo reverts everything the sync did (copied files disappear again; overwritten and deleted files come back with their contents). Five generations of backups are kept under folder_sync_backup in the app's data folder, with the oldest cleaned up automatically.

• A failure does not stop the run. If a file cannot be opened or written, the rest still goes through and the number of failures is reported at the end. Only what succeeded is included in the undo.

• Only files are synced. Folders themselves are not transferred, but the parent folders needed at the destination are created automatically.

• Comparing is free; the sync is limited to 3 uses in the free version.

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