Part of it is decentralized, the challenges module. Planning to move further on decentralizing more and more of the product (during the past 3 years we develope

Part of it is decentralized, the challenges module. Planning to move further on decentralizing more and more of the product (during the past 3 years we developed it in a centralized manner), but its not that practical now, given the fact that we need storage, tons of micro-transactions with 0 fees for the end user. So, yes, using Ethereum blockchain, not fully decentralzied, and we might switch to a dPOS blockchain in the near future (if EOS, SMT succeed).