Creating a website builder, what tools, algorithm?

Question

Wix

What knowledge (tools) does a programming team need to create a drag'n'drop website builder in the editor (like wix.com)?
The question is asked for the purpose of personal interest. Who knows, answer. Thank you.

Answer 1

they are many in flash
In general Ajax, HTML5, CSS3, Drag'n'drop (usually take jquery-ui). Anything on the server side.