Looking for a white-labelled WYSIWYG page builder solution

Hello all. I'm building a SAAS and one of the features is to enable my users to build documents in the app and send them out for e-signatures. I don't want to build out a WYSIWYG page builder if I can buy it from a white-labelled solution provider.

Does anyone know if such a service exists? I'm contacting some of the website builder companies. Just wanted to get the community's input.

Thank you.