Skewer
Live web development in Emacs
...Multiple browser windows or tabs may connect simultaneously and receive the same submitted code. The package includes an Emacs-hosted HTTP service, CORS support, and a userscript for attaching Skewer to arbitrary pages. It is written entirely in Emacs Lisp and is distributed through MELPA with its required dependencies. The project supports major desktop browsers and uses key bindings modeled after Emacs Lisp development modes.