White-label is a vendor offering where the customer's brand replaces the vendor's identity across every user-facing surface. For SaaS document tools, this means: custom domain (share.yourdomain.com), customer logo and colors, customer favicon, transactional emails from the customer's address, and zero mention of the underlying vendor on viewer pages, signature flows, or completion certificates.
White-label is especially valuable for agencies (clients see the agency, not the underlying tool), for enterprises with strict brand controls, and for embedded SaaS where the document workflow is part of another product.