Canjs
Can do JS, better, faster, easier.
Serenade.js
Client side MVC framework
Pegasus
Load data while still loading other scripts and display data faster in jQuery, Backbone, Angular, ... apps
Stapes
a (really) tiny Javascript MVC microframework
Prime
an OOP javascript library for node.js and the browsers
Jade
Jade - robust, elegant, feature rich template engine for nodejs
Thinkjs
Use full ES2015+ features to develop Node.js applications, Support TypeScript.
Lunr.js
A bit like Solr, but much smaller and not as bright
jTypes
jTypes is the most comprehensive and robust JavaScript library for overcoming differential inheritance with prototype-based objects. Its lightweight yet powerful design provides web programmers on any platform or browser the ability to emulate classical inheritance where objects are defined by classes.
Hermes.js
Message and Error logger implementation
Regular
a living template engine that helping us to create data-driven component.
Mask Js
Zen Coding | Markup | Template | HMVC
Lazy Load Xt
Lazy load XT is a jQuery plugin for images, videos and other media
Aura
A scalable, event-driven JavaScript architecture for developing widget-based applications. Works with Backbone.js and other frameworks.
101
A modern JS utility library
YUI3
YUI is a free, open source JavaScript and CSS library for building richly interactive web applications.
Boiler
Boiler is a utility library that makes every day tasks in JavaScript easier by providing over 115 methods that work on arrays, collections, functions, numbers, objects, and strings.