QUnit
Jasmine
Ava
Karma
WebdriverIO
Enzyme
Mocha
Chai
kdiff3
Beyond Compare
WinMerge
Meld
Araxis Merge
DiffMerge
P4Merge
Devart Code Compare
QUnit
kdiff3Jasmine - Behavior-Driven JavaScript
Beyond Compare - Beyond Compare allows you to compare files and folders.
Ava - Making conversations accessible for the deaf
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
Karma - Spectacular Test Runner for JavaScript
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.