We are currently using a custom contact form on our website and we'd like to use the Marketo form API to send the fields to Marketo instead of loading the Marketo form on the page. This because we'd like to keep the current design of the form and use a string to post the data. Anyone familiar with how to do this?
Yes, initially described at/blogs/marketowhisperer/2015/09/30/make-a-marketo-form-submission-in-the-background and discussed in many other posts.
"Use a string" is rather vague, you want to use the JS described.