Nick Johnson, founder and lead developer of Ethereum Name Service (ENS), has written an open letter on X (formerly Twitter) urging Unstoppable Domains to drop a patent or face a lawsuit. Unstoppable Domains was granted a patent in January that claims to use blockchain technology to determine domains. Johnson claims that the patent is based on innovations developed by ENS and contains no novel innovations of its own. Johnson has requested that Unstoppable Domains put legal weight behind its PR commitment to pledge its patent to the Web3 Domain Alliance.