Polymer is a library that uses the latest web technologies to let you create custom HTML elements. Build anything from a button to a complete application as an encapsulated, reusable element that works across desktop and mobile.

Mojo.JS is described as 'A non-opinionated, totally customizable JavaScript framework designed for writing programs that scale across any platform' and is an app in the development category. There are more than 50 alternatives to Mojo.JS for a variety of platforms, including Windows, Linux, Mac, Self-Hosted and Web-based apps. The best Mojo.JS alternative is Vue.js, which is both free and Open Source. Other great apps like Mojo.JS are Angular, Svelte, Vite and Meteor.
Polymer is a library that uses the latest web technologies to let you create custom HTML elements. Build anything from a button to a complete application as an encapsulated, reusable element that works across desktop and mobile.

Opa is an open source, simple and unified platform for writing web applications. All aspects are directly written in Opa: Frontend code, backend code, database queries and configuration. And everything is strongly statically typed.
An efficient server implies a lower cost of the infrastructure, a better responsiveness under load and happy users. How can you efficiently handle the resources of your server, knowing that you are serving the highest number of requests possible, without sacrificing security...
Zepto is a minimalist JavaScript library for modern browsers with a largely jQuery-compatible API.
MVC framework making it easy to write realtime, collaborative applications that run in both Node.js and browsers.
Expressive middleware for node.js using generators via co to make web applications and APIs more enjoyable to write. Koa's middleware flow in a stack-like manner allowing you to perform actions downstream, then filter and manipulate the response upstream.
Sails.js make it easy to build custom, enterprise-grade Node.js apps. It is designed to mimic the MVC pattern of frameworks like Ruby on Rails, but with support for the requirements of modern apps: data-driven APIs with scalable, service-oriented architecture.
Aurelia is a JavaScript client framework that leverages simple conventions to empower your creativity.

Durandal is a cross-device, cross-platform client framework written in JavaScript and designed to make Single Page Applications (SPAs) easy to create and maintain.
The Famous Engine is a free and open source JavaScript rendering engine. What makes the Famous Engine unique is its JavaScript rendering engine and 3D physics engine that gives developers the power and tools to build native quality apps and animations using pure JavaScript.