Receive an email notification when my form is submitted using the API

How do I get notified if a form has been submitted using API?

It would be great if you can also integrate google spreadsheet with that. So that as soon as a form is filled using API google sheets gets updated?

You can enable Jotform integration with Google Spreadsheet. Inside of this article you can find out how to do it:

http://www.jotform.com/blog/57-Google-Docs-Integration-Send-Responses-to-Google-Spreadsheets-Instantly- 

In case that you want to use API it is better to contact API team through this email address api@jotform.com because they are more familiar with this topic. 

I found one article on Stackoverflow that can help you maybe:

http://stackoverflow.com/questions/16183127/trigger-google-apps-script-when-jotform-submitted-and-integrated-to-spreadsheet 

Hope this will help. Let us know if you need further assistance.