Excerpt from page 4 of YAPPADAPPADOO Whitepaper:
The yappadappadoo Store is the first and currently the only app store for PWA with links to the Blockchain for payments, smart contracting, app selection and reviews. Therefore, yappadappadoo does not store any personal user data we operate with Blockchain-IDs only.
This is one of the features of YAPPADAPPADOO platform, the Blockchain-ID. This feature will really provide high security on personal user data because every transaction will be identified through Blockchain-ID only. Preventive measures were being implemented because some private data sometimes leak and sometimes identity theft occurs.