Bundlers

• webpack - Packs CommonJs/AMD modules for the browser.
• Parcel - Blazing fast, zero configuration web application bundler.

ES6

Other

• Babel (Formerly 6to5) - Turn ES6+ code into vanilla ES5 with no runtime.

Frameworks

Other

• DataFormsJS - A minimal JavaScript Framework and standalone components for rapid development of sites and SPA's.

Generators

Other

• Gatsby.js - React-based static site generator.
• Next.js - React powered static site generator, and they say "All the tools you need to make the Web. Faster.".

MVC Frameworks and Libraries

Runner

• svelte - Svelte is a new way to build web applications. It's a compiler that takes your declarative components and converts them into efficient JavaScript that surgically updates the DOM.
• Million - <1kb compiler-focused virtual DOM. It's fast!