Reputation systems are crucial for distributed applications in which users have to be made accountable for their actions, such as ecommerce websites. However, existing systems often disclose the identity of the raters, which might deter honest users from posting reviews, out of fear of retaliation from the ratees. While many privacy-preserving reputation systems have been proposed, none of them was at the same time truly decentralized, trustless, and suitable for real world usage in, for example, e-commerce applications. After discussing the weaknesses and shortcoming of existing solutions, we will present our own blockchainbased trustless reputation system, and analyze its correctness and the security guarantees it promises.