The problem zkPayroll solves

zkPayroll is dApp built on top zkBob stablecoin. It facilitates DAO, corporations, and Individual to generate invoices and salary payments.

Challenges I ran into

zkPayroll is maintaining meta-data for zkBob based payments for many users.
It was challenging to develop an easily updatable and retrieval process for all this stored data without relieving the actual recipient's personal information to the world.

As this payments will be happening weekly/monthly/ad-hoc bases, Tree based retrival process has been developed to store and fetch information.
For hiding personal information all the information are hashed so only sender and receiver will be able to verify the contents and purpose for transaction of zkBob.