Embeddable Web UI Designer

Is there are web framework that allows creating of custom Web UI designers that can be embedded into a webpage/webapp?

What I am looking for is to create a web UI that allows users to edit the UI in a drag and drop style editor. It should be possible to select some widgets (like these: http://ift.tt/1khJbOQ) and to select a data source (will be provided by back-end, nodejs).

Background: I am not a web designer and have no previous web experience. I just want to know if it possible to create what I am looking for and how much effort it would be. My background is in embedded Linux development and I would like to create an easy way for people to create machines with single board computers. The embedded stuff is pretty much complete and I am exploring ways to create nice and user editable user interfaces.