The problem Venrate solves

For as long as influence can be bought or sold freely, there is little incentive for such vendors to maintain online reputation scores. With blockchain technology, however, there might be a way to change how online reputation is managed. Building a decentralized reputation as a smart contract offers a standardized way of accessing reputation data that has been accumulated, where more verifications across platforms can reinforce the reliability of any one reputation score.

Challenges I ran into

Adding multiple accounts to one DID and calculating the credit scores based on past transactions. It's hard getting all the transaction records of multiple accounts associated with one DID.