If you’re using our SOAP API or Munchkin API, Custom Object Metadata Schema can be exported. Here’s how to get it.
In My Marketo, click Admin.
Click Marketo Custom Objects.
Select the Marketo Custom Object you want to export.
Click the Custom Object Actions drop-down and select Export Object.
The Custom Object must be in Approved State to be exported.
You now have a spreadsheet with the Schema of the Custom Object, across three tabs.