kdiff3
Beyond Compare
WinMerge
Meld
Araxis Merge
DiffMerge
P4Merge
Devart Code Compare
NNote
JustNotepad.com
NoteAway
PlicPad
Vov Text Edit Plus
TakeNote
Midnight.Pub
recordando
kdiff3Beyond Compare - Beyond Compare allows you to compare files and folders.
JustNotepad.com - A free online notepad allows you to create any text or notes in your web browser.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
NoteAway - NoteAway is the simplest, most convenient way to take quick notes on OS X.
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.
PlicPad - Shareable notepad without urls