This will let user make any kind of graph by supplying json, xml , docx, xls or csv files.
you can choose the graph and get the view of the graph now you can get the code and you can view the graph to your site as well.
Initially this service should be free for all (first year) and it should cost Rs 50 /- per year.
front end: angularjs, foundation, gruntjs , minified js , compiled css, jslint or jshint for testing js code quality.
backend : ror, webrick, postgres, cookie or token based authentication
learn ror from dave jones videos on youtube till them make a proper front end , wireframe the design and then make and angular based front end refer thinkster.io angular-rails tutorial for that