It's pretty straightforward, you can check it out in my profile JSON or @ابو مريم's. It looks something like this: Structure: content = JSON string with all the fields (including just the first NIP-05 for compatibility) tags = Array with all the NIP-05s as separate ["nip05", "..."] entries Other clients only parse content.nip05, so they see one. The ones that support it read the tags, so they see both.