By custody-address

curl --request GET \
  --url https://api.neynar.com/v2/farcaster/user/custody-address \
  --header 'x-api-key: <api-key>'

{
  "user": {
    "object": "user",
    "fid": 3,
    "username": "<string>",
    "display_name": "<string>",
    "custody_address": "0x5a927ac639636e534b678e81768ca19e2c6280b7",
    "pfp_url": "<string>",
    "profile": {
      "bio": {
        "text": "<string>",
        "mentioned_profiles": [
          {
            "object": "user_dehydrated",
            "fid": 3,
            "username": "<string>",
            "display_name": "<string>",
            "pfp_url": "<string>",
            "custody_address": "0x5a927ac639636e534b678e81768ca19e2c6280b7"
          }
        ],
        "mentioned_profiles_ranges": [
          {
            "start": 1,
            "end": 1
          }
        ],
        "mentioned_channels": [
          {
            "id": "<string>",
            "name": "<string>",
            "object": "channel_dehydrated",
            "image_url": "<string>",
            "viewer_context": {
              "following": true,
              "role": "member"
            }
          }
        ],
        "mentioned_channels_ranges": [
          {
            "start": 1,
            "end": 1
          }
        ]
      },
      "location": {
        "latitude": 0,
        "longitude": 0,
        "address": {
          "city": "<string>",
          "state": "<string>",
          "state_code": "<string>",
          "country": "<string>",
          "country_code": "<string>"
        }
      }
    },
    "follower_count": 123,
    "following_count": 123,
    "verifications": [
      "0x5a927ac639636e534b678e81768ca19e2c6280b7"
    ],
    "verified_addresses": {
      "eth_addresses": [
        "0x5a927ac639636e534b678e81768ca19e2c6280b7"
      ],
      "sol_addresses": [
        "<string>"
      ],
      "primary": {
        "eth_address": "0x5a927ac639636e534b678e81768ca19e2c6280b7",
        "sol_address": "<string>"
      }
    },
    "verified_accounts": [
      {
        "platform": "x",
        "username": "<string>"
      }
    ],
    "power_badge": true,
    "experimental": {
      "neynar_user_score": 123
    },
    "viewer_context": {
      "following": true,
      "followed_by": true,
      "blocking": true,
      "blocked_by": true
    }
  }
}