xREL.v3

curl https://api.xrel.to/v2/oauth2/auth?response_type=code&client_id=1gAKr9nlKevvbqi2uVddhAj70kwyyfsOsRI&redirect_uri=urn:ietf:wgauth:2.0ob&state=&scope=addproof

{
    "error_type": "oauth2",
    "error": "invalid_scope",
    "error_description": "The requested scope is invalid, unknown, or malformed Check the `addproof` scope"
}