what's Ultra Sound Relay?

Ultra Sound Relay is a credibly neutral and permissionless MEV-Boost relay for Ethereum, developed by the ultrasound.money team as a public good. It upholds proposer-builder separation (PBS) principles by validating submitted blocks against consensus rules, reducing weak censorship risks. Relay operators commit to not participating in searching or block building and self-limit to one-third of blocks to maintain decentralization. It provides builders with advanced tools including geo-distributed auctions (e.g., Tokyo for ultra-low latency), optimistic V3 bidding processed locally per proposer location, automatic bid adjustments to second-highest +1 wei, and optional OFAC filtering. High adoption with over 44% historical block inclusions supports validator rewards via fair MEV auctions and ecosystem integrations like MEV-Protect.