Vue.js - Reactive Components for Modern Web Interfaces
Beyond Compare - Beyond Compare allows you to compare files and folders.
Deku - Functional view library for building UI components as an alternative to React
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
Polymer - Polymer is a library that uses the latest web technologies to let you create custom HTML elements.
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.