Api Endpoint

Base ERC721 NFT Owner Lookup

Look up the current owner of one ERC-721 token on Base with ownerOf(uint256). Accepts a strict contract address and uint256 decimal token ID, performs one read-only eth_call with bounded public-RPC fallback, and returns the normalized owner address. Reverts, non-contracts, nonexistent tokens, malformed responses, and upstream failures return non-2xx and do not settle.

Open interactive test console

Offering

Provider: nft.fablerlabs.com
Method: GET
Offering type: Api Endpoint
Transport type: http
Category: Blockchain And Crypto
Delivery: Not provided
Pricing model: Not provided
x402 version: 2

Endpoint context

URL: https://nft.fablerlabs.com/nft/owner
MIME type: application/json
First seen: 2026-10-16T02:58:03.930Z
Last seen: 2026-11-02T08:03:02.653Z
Tags: Crypto

Website

Payment pricing

x402 payment terms are the authoritative price for calling this endpoint.

Payment option 1: 0.003 USDC
Atomic price: 3000 · Network: eip155:8453 · Asset: USDC · Scheme: exact

Raw x402 terms

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "3000",
    "payTo": "0x65E3E64935eA709bDf1119E1fC991299c04c0154"
  }
]

Observed health

Status: Healthy
Latest latency: 1204 ms
Average latency: 845 ms
HTTP status: 402
Last checked: 2026-11-02T08:03:02.648Z
Reachability: 100% over 14 checks

Latency is measured to the first response headers. A reachable result does not verify response accuracy or merchant identity.

Input schema

{
  "type": "object",
  "properties": {
    "type": {
      "type": "string",
      "const": "http"
    },
    "method": {
      "type": "string",
      "enum": [
        "GET"
      ]
    },
    "queryParams": {
      "type": "object",
      "properties": {
        "contract": {
          "type": "string",
          "pattern": "^0x[0-9a-fA-F]{40}$",
          "description": "ERC-721 contract address on Base."
        },
        "token_id": {
          "type": "string",
          "pattern": "^(0|[1-9][0-9]{0,77})$",
          "description": "Canonical unsigned decimal uint256 token ID."
        }
      },
      "required": [
        "contract",
        "token_id"
      ],
      "additionalProperties": false
    }
  },
  "required": [
    "type",
    "method"
  ],
  "additionalProperties": false
}

Output schema

{
  "type": "object",
  "properties": {
    "type": {
      "type": "string"
    },
    "example": {
      "type": "object",
      "properties": {
        "chain": {
          "type": "object",
          "properties": {
            "name": {
              "type": "string",
              "const": "Base"
            },
            "chain_id": {
              "type": "integer",
              "const": 8453
            },
            "caip2": {
              "type": "string",
              "const": "eip155:8453"
            }
          },
          "required": [
            "name",
            "chain_id",
            "caip2"
          ]
        },
        "contract": {
          "type": "string",
          "pattern": "^0x[0-9a-f]{40}$"
        },
        "token_id": {
          "type": "string",
          "pattern": "^(0|[1-9][0-9]*)$"
        },
        "owner": {
          "type": "string",
          "pattern": "^0x[0-9a-f]{40}$"
        },
        "block_tag": {
          "type": "string",
          "const": "latest"
        },
        "upstream": {
          "type": "string",
          "enum": [
            "https://mainnet.base.org",
            "https://base-rpc.publicnode.com"
          ]
        },
        "as_of": {
          "type": "string",
          "format": "date-time"
        }
      },
      "required": [
        "chain",
        "contract",
        "token_id",
        "owner",
        "block_tag",
        "upstream",
        "as_of"
      ]
    }
  },
  "required": [
    "type"
  ]
}