this plugin is great

This plugin works great with Gravity Forms for sending leads to Marketo. It deserves a much higher star rating than it is currently getting.

You need to understand Marketo in order to use it.

For example, to get Marketo custom fields to sync, you need to know Marketo’s internal name for the field.

In Marketo go to Admin > Field Management and click on the name of the field you want to populate. What you are looking for is a variation of the field name that uses underscores instead of spaces (if one exists), for example we have a lead field named “Lead Source Detail”. Marketo’s internal name for it is Lead_Source_Detail_c. This is what you use when mapping fields from your form to custom Marketo fields.

Thank you Zach.