# ERC-721 Tokens Of Owner Lookup

> ERC-721 Tokens Of Owner Lookup is a paid API for AI agents from biosfera.46-62-215-147.sslip.io, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-01).

Returns the token IDs of an ERC-721 NFT collection owned by a specific wallet address on Base, Ethereum, Arbitrum, Optimism, or Polygon, with pagination and total balance.

## Facts

- Endpoint: GET https://biosfera.46-62-215-147.sslip.io/o/erc721-tokens-of-owner?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/erc-721-tokens-of-owner-lookup-ab906324
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lykahO6np6Ec0xdDaBFXC

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability erc-721-tokens-of-owner-lookup-ab906324
```

Example prompt: Which token IDs from the ERC-721 collection at 0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D does the wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 own on Ethereum?

## When to prefer this

Use this endpoint when you need to enumerate specific token IDs an address owns within a known ERC-721 contract on Base, Ethereum, Arbitrum, Optimism, or Polygon. It is the right choice when you need paginated token ID lists (not just balances) and when the collection implements the ERC-721 Enumerable extension. Prefer this over a general NFT indexer when you want lightweight, on-chain verified ownership data per collection without relying on third-party NFT databases.

## Known failure modes

- Collection is not enumerable — response states enumeration is unsupported
- Invalid or non-checksummed wallet/contract address — returns validation error
- Unsupported chain value — returns error for chains outside the allowed enum
- Offset out of range — no results returned if offset exceeds total balance
- Network or RPC timeout — transient failure with no token data returned
- Address owns zero tokens in the collection — returns empty list with balance 0

## How this service works

Use when you need which token ids of an ERC-721 collection an address owns on Base, Ethereum, Arbitrum, Optimism or Polygon. Works for enumerable collections (tokenOfOwnerByIndex); returns up to 50 ids per page with the total balance, and says when the collection is not enumerable.

## Output

Returns a paginated list of up to 50 token IDs owned by the specified address within the given ERC-721 contract, along with the total balance (count of tokens owned). If the collection does not implement the enumerable extension (tokenOfOwnerByIndex), the response indicates that enumeration is not supported.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "chain",
      "contract",
      "address"
     ],
     "properties": {
      "chain": {
       "enum": [
        "base",
        "ethereum",
        "arbitrum",
        "optimism",
        "polygon"
       ],
       "type": "string"
      },
      "offset": {
       "type": "integer",
       "maximum": 100000,
       "minimum": 0
      },
      "address": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$"
      },
      "contract": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc-721-tokens-of-owner-lookup-ab906324/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from biosfera.46-62-215-147.sslip.io](https://www.zero.xyz/host/biosfera.46-62-215-147.sslip.io/llms.txt)