There are Yeoman and Grunt .
I would think that Yeoman is the simplest, it is based on the Grunt and yeoman server you can get a live reboot and compilation of JS and CSS files. It also supports other things. If you only need a live view and change it. files you can use yeoman watch . It requires you to install Gruntfile.js, but there are some nice examples.
You can also just use Grunt.js, for this you will need to install additional tasks, but this is not a big problem.
In short, with youman you get some extra features out of the box, but it is based on Grunt, and I can recommend both. They work through the command line interface, but it is quite easy. Check your websites and try them, for free!
Youtube entry to Yeomen, with Addi Osmani
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