No, unfortunately there is no such conversion tool. You have to recreate the forms...

 regards,

 Tomasz

This could be what you are looking for: 

FormTrek  

Microsoft has announced that it is retiring the Office InfoPath platform. See the announcement here. InfoPath 2013 is the final version of the product and will be supported until 2023. The forms product will not be supported on future versions of SharePoint online. This will leave organizations heavily invested in InfoPath searching for another forms solution.

FormTrek is currently developing the InfoPath to Nintex form migration tool. Below is a brief demonstrations of our current solution.

Sushil Pai‌, I work with a small group of developers working to tackle this specific issue for getting InfoPath forms to Nintex. Check out our site www.infopath2nintex.com and sign up for the beta. It's going well do far but we can always use more forms and customer feedback.

One of the biggest things we've seen is the complexity in the custom code and how that translates to Nintex. We are aiming to help user figure this out.

Thank you, will do. I will submit my feedback on that as i try it.

sushilspai Did you end up using the migration tool? Was it any good?