The Marketo REST Asset API was released in the March 2015 release. This API allows to access Marketo’s file, folder, token, email, and email template objects.
Note that two role permissions were added to provide access to the Asset API endpoints: Read-Only Assets, Read-Write Assets. If your API user role predates the release of the Asset APIs, then you will need to create a new API user role with these permissions to enable access. Otherwise, you will receive a 603 “Access Denied” error response.
In addition to the release of the REST Asset API, there were updates to existing REST API endpoints. The Merge Lead REST API endpoint was updated to allow for merging of multiple leads. The Schedule Campaign REST API endpoint was updated to allow for cloning of a campaign while scheduling a campaign. The Create/Update Leads REST API endpoint was updated to allow for changing of a lead’s partition.