guide · file explorer

Compare two files with a right-click in File Explorer

You are in File Explorer and have two files in front of you: a report and its earlier version, a download and the copy you already had, two folders that should hold the same thing. Select both, right-click, choose Compare with Diffoniq, and the comparison is open. No dialog, no typing paths.

The short version: in Diffoniq, switch on Options → Show in Explorer’s Context Menu once and restart Explorer. Then select two files or two folders and right-click. For two items in different folders, right-click the first and choose Select Left Side for Diffoniq, then right-click the second and choose Compare to.

1. Turn on the right-click entry

Start Diffoniq and choose Options → Show in Explorer’s Context Menu. It takes a few seconds, because Windows registers a small package for it; then the menu item shows a check mark. The setup never adds the entry by itself, it applies to your own Windows user account only, and it needs no administrator rights.

The entry appears once Explorer restarts: at your next sign-in, or right away in Task Manager with Windows Explorer → Restart (open folder windows close). On Windows 11 it sits directly in the right-click menu, not only under Show more options; Windows places it among the entries of your other installed tools, so it is not necessarily at the top. Windows 10 shows it too, from version 2004.

The entry is served by DiffoniqShell.exe, a small program next to Diffoniq.exe. Nothing of Diffoniq runs inside Explorer. It works with the installed and the portable version alike. Details: Explorer’s Context Menu.

2. Compare two files or two folders

Select two files in the same folder, for example with Ctrl+click, right-click one of them and choose Compare with Diffoniq. Diffoniq opens and shows both side by side, with the changed lines marked.

Windows 11 File Explorer right-click menu on two selected files, File2.txt and File10.txt, with the entry Compare with Diffoniq; the Windows entries are in German — **Two files selected, one right-click.** Shown on a German Windows 11, entries of other installed tools removed; the Diffoniq entry is in English.

Which file lands on the left? The one that comes first by name, the way Explorer sorts by name: File2 before File10. In a list sorted by name, that is the upper one, whichever of the two you right-click. Swap Sides turns them around.

Diffoniq window after Compare with Diffoniq on File2.txt and File10.txt in File Explorer: File2.txt on the left, File10.txt on the right, three lines each; line 2 reads beta on the left and BETA on the right; the status bar reads 1 changed — **Right-clicked on File10.txt, File2.txt is still on the left.** Diffoniq orders the two by name, as File Explorer does.

Two folders work the same way and open as a folder comparison: which files differ, which exist on one side only. From there, two folders can also be synchronized with the Synchronize command. More in Compare two folders on Windows, and how to read a file comparison in Compare two text files on Windows.

3. Compare files from two different folders

Often the two files are not in the same folder: the copy on the USB stick and the one in Documents, last month’s export and this month’s. Then pick them one after the other:

Right-click the first file and choose Select Left Side for Diffoniq. Nothing opens yet; Diffoniq remembers it.
Go to the second file, right-click it and choose Compare to “name”, where name is the file you picked first. The comparison opens with the first file on the left. Afterwards the left side is forgotten.

Windows 11 File Explorer right-click menu on report.txt in a second folder, after report.txt in the first folder was selected as the left side: the entry reads Compare to report.txt — **The second file, in another folder.** The entry names the file you selected first. Shown on a German Windows 11, entries of other installed tools removed.

Picked the wrong one? Right-click it again and choose Clear Left Side for Diffoniq. The left side is kept until you use it, also across a restart; if the file no longer exists, Compare to is not offered. Folders work the same way: right-click a folder to select it as the left side, then right-click the other folder.

4. What gets compared

You select	Diffoniq
Two files, or two folders	compares them; the one first by name is on the left
A file and a folder	compares the file with the file of the same name inside the folder; without such a file, both are shown as they are
A ZIP archive and a folder	compares the archive’s contents with the folder, like two folders
More than two items	says which two it compares and which it leaves out, then compares the first two by name

The file-and-folder rule saves a step: next to the new report.txt there is a folder old with the previous report.txt in it. Select the file and the folder, and the two files are compared, not the file against the whole folder. Two items dropped onto the Diffoniq window are paired by the same rules.

5. Or use “Send to”

If you prefer the classic way, switch on Options → Show in Explorer’s “Send to” Menu. Then select two files or two folders, right-click and choose Send to → Diffoniq. On Windows 11, Send to is under Show more options.

Nothing is installed into Explorer for this. The entry is an ordinary shortcut in your Send to folder, kept per Windows user, and it follows the same rules as the table above. With one item selected, Diffoniq opens the selection dialog with it on the left and waits for the other side. Both entries are independent: you can have either, both or neither. Details: Explorer’s “Send to” Menu.

Good to know

Comparing changes nothing. A file is only written when you take lines over and press Ctrl+S, and then the original is kept as a .BAK file.
Turning it off: click the same menu item again. Explorer notices at its next restart, as when turning it on. Uninstalling Diffoniq removes the entries of the user who runs the uninstall.
Portable version moved, or updated? The next start of Diffoniq with the option on renews the entry, so it points at the copy you use now.
Inside Diffoniq, the right-click menu of a file in a folder comparison shows the same Explorer menu, but without the Diffoniq entry: you are already comparing there.

Other ways to start a comparison

Without the right-click entry, drag two files from File Explorer onto the Diffoniq window, or press Ctrl+O and enter both paths. From a command prompt or a script:

"C:\Program Files\Diffoniq\Diffoniq.exe" "D:\reports\report.txt" "E:\backup\report.txt"

That is the installer’s path; the portable version runs from the folder you unpacked it to. Windows itself has no compare entry in File Explorer; the closest built-in tool is fc in the command prompt, which prints the differing lines without a side-by-side view. Free tools such as WinMerge add their own right-click entries; our comparison page shows how they differ from Diffoniq, with the date we checked.

Questions

I switched it on, but there is no entry. Why? Explorer only reads the change when it starts. Restart it in Task Manager (Windows Explorer → Restart) or sign out and in again.

Do I need administrator rights? No. Both entries apply to your own Windows user account only.

Which file ends up on the left? The one that comes first by name, as in Explorer sorted by name. With Select Left Side and Compare to you decide yourself.

Can I compare two files in different folders? Yes, with Select Left Side for Diffoniq on the first and Compare to on the second (step 3).

Which Windows versions does it run on? Windows 10 (the right-click entry from version 2004) and Windows 11, 64-bit.

Try it from your own File Explorer

Diffoniq runs on Windows 10 and 11, 64-bit. Every feature is available for 30 days before you decide.

Try Diffoniq free for 30 days See pricing

Windows is a trademark of Microsoft Corporation. WinMerge is a trademark of its respective owner. Diffoniq is not affiliated with any of them.