Add "Open in Notepad" to the right-click menu for every file — via Microsoft Learn

Registry change

Double-click a .reg file and confirm to merge it. Right-click → Edit first if you want to read it, which is always a good idea with any .reg file from the internet.

Apply

Windows Registry Editor Version 5.00

; Oddbyte.Me: Add "Open in Notepad" to the right-click menu for every file

[HKEY_CURRENT_USER\Software\Classes\*\shell\OpenInNotepad]
@="Open in Notepad"
"MultiSelectModel"="Single"

[HKEY_CURRENT_USER\Software\Classes\*\shell\OpenInNotepad\command]
@="notepad.exe \"%1\""

Undo

Windows Registry Editor Version 5.00

; Oddbyte.Me: undo Add "Open in Notepad" to the right-click menu for every file

[-HKEY_CURRENT_USER\Software\Classes\*\shell\OpenInNotepad]

Same thing from a command prompt

Run in a normal (non-admin) Command Prompt or Terminal.

reg add "HKCU\Software\Classes\*\shell\OpenInNotepad" /ve /t REG_SZ /d "Open in Notepad" /f
reg add "HKCU\Software\Classes\*\shell\OpenInNotepad" /v "MultiSelectModel" /t REG_SZ /d "Single" /f
reg add "HKCU\Software\Classes\*\shell\OpenInNotepad\command" /ve /t REG_SZ /d "notepad.exe "%1"" /f

Undo:

reg delete "HKCU\Software\Classes\*\shell\OpenInNotepad" /f

On Windows 11 custom commands like this appear in the full menu (Show more options, or Shift + right-click), not the short one. MultiSelectModel = Single hides the command when several files are selected so you can't open dozens of Notepad windows by accident. Want it to appear only with Shift held? Also add an empty string value named Extended to the OpenInNotepad key. You can rename the label or point the command at another editor.