Export Custom Fields

I am considering recommending Workdrive for a client who wants to manage 10,000 digital assets (photographs).

They will want to use custom fields to add information to these photos. My issue is that (as far as I can see) there is no way to export all of the custom field data mapped to the file name. If the client ever needs to move from Zoho drive to another service, they need to be able to preserve all of the data they've entered into custom fields. Is this possible?

Another question: If I want to show files from the Workdrive in a website gallery, I'd like to also show data from the custom fields on the website, is there any kind of working API access to get all of this data in JSON format?

Thank you.