Setting Up the Notepad++ Compare Plugin

Guide · Published September 2026

Notepad++ is the default text editor on a lot of Windows machines, and the first thing people discover when they try to diff two files in it is that the feature is not there. File comparison lives in the Compare plugin, and a stock install does not include it.

Installing the Compare plugin

1. Open Plugins → Plugins Admin.
2. Search the list for Compare and tick its checkbox.
3. Click Install. Notepad++ closes and reopens to finish installing.

On older versions the menu is called Plugin Manager rather than Plugins Admin, and on some managed corporate installs the plugin manager is disabled entirely — if it is, the browser route below is the practical workaround. The plugin is also 64-bit/32-bit specific, so if Notepad++ was reinstalled in the other architecture the Compare entry can vanish from the Plugins menu and need reinstalling from Plugins Admin a second time.

Running the comparison

Open both files as tabs in the same Notepad++ window, then choose Plugins → Compare → Compare, or press Alt+D. The window splits into two panes, scroll-locked together, with differences colour-coded: added lines in one colour, removed in another, changed lines marked in both panes. Plugins → Compare → Clear Results (or Ctrl+Alt+D) closes the comparison view.

The plugin needs exactly two files to work with. If the Compare command is greyed out, that is nearly always the reason — one tab open, or several with no clear pair.

Making the output readable

Two settings under Plugins → Compare → Settings dramatically reduce noise on real files. Ignore spaces stops indentation-only changes from dominating the result, which matters if the two files were edited in different editors. And detecting moved lines separately keeps a block that simply moved from showing as a large deletion plus a large insertion.

The line-ending trap

If a comparison marks every line as different, the two files almost certainly have different line endings — one saved with Windows CRLF, the other with Unix LF. Notepad++ shows the current file’s ending in the status bar, and Edit → EOL Conversion converts one to match the other. Do that before concluding the files have nothing in common.

When a browser diff is the better option

The plugin is the right tool for files on your machine when you already work in Notepad++. It is the wrong tool in three situations: you are on a machine where you cannot install plugins, you are not on Windows at all, or you just need a quick one-off comparison of text you already have in the clipboard. In those cases paste both versions into the browser text diff — same line-by-line result, no install, and the comparison runs locally in the tab rather than being uploaded anywhere. Full walkthrough in comparing two text files online.

When the files are lists, not prose

If the two files are exported lists — IDs, SKUs, email addresses — a line-by-line diff is the wrong shape of answer. Re-sorting one export would make every line look changed even though the data is identical. Use a set comparison instead, which ignores order and simply reports what exists in one file and not the other. The list comparison tool does this, and the CSV guide covers picking a key column when the files have multiple columns.