Koa.js provides a promise-based API that's well-suited to be used with async functions. It has the distinction of being the official successor to Express (creat

Koa.js provides a promise-based API that's well-suited to be used with async functions. It has the distinction of being the official successor to Express (created by the same people). Having used it for several years now, I find Express feels a bit kludgy and error-prone. That said, Express will be around for quite some time, due to its name-recognition and large install base.