We accept all file types. For example,.csv,.bmp,.mp3,.gpg,.css,.doc,.gif, zip,.htm,.docx,.jpeg,.jpg,.png,.pdf, and.stf
Noted - Except for files that Salesforce does not accept, only those files we are not supporting.
PS: View Mass File Upload, Salesforce file upload app, on Salesforce AppExchange: https://appexchange.salesforce.com/appxListingDetail?listingId=82cf236b-1ee8-4ea7-aebf-fd0c89fb93bd