# Ethereum ERC-721 Token IDs by Owner

> Ethereum ERC-721 Token IDs by Owner is a paid API for AI agents from api.arysphere.com, paid per call via x402, $0.008/call, status unknown (last checked 2026-10-29).

Returns all ERC-721 NFT token IDs held by a given address in a specified ERC-721 collection on Ethereum mainnet, read from the latest chain state.

## Facts

- Endpoint: POST https://api.arysphere.com/v1/ventures/x402_eth_reads_v1/eth_mainnet_erc721_tokens_of?utm_source=zero.xyz
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ethereum-erc-721-token-ids-by-owner-e9e98ed2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-vYCjz36rKdeJHDGJ4nrt

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 ethereum-erc-721-token-ids-by-owner-e9e98ed2 -d '<json body>'
```

Example prompt: Can you list all the NFT token IDs that wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 holds in the Bored Ape Yacht Club contract 0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D on Ethereum mainnet?

## When to prefer this

Use this endpoint when you need to enumerate all token IDs an address owns within a specific ERC-721 collection on Ethereum mainnet, especially when the contract implements the ERC-721 Enumerable extension. Prefer this over general NFT indexers when you need authoritative, on-chain state at the latest block rather than potentially lagged indexed data. It is well-suited for ownership verification, portfolio snapshots, and gating logic tied to specific collections.

## Known failure modes

- Invalid owner address format (must be 0x + 40 hex chars) — request rejected
- Invalid contract address format — request rejected
- Contract does not implement ERC-721 Enumerable — enumeration may fail or return empty
- Address holds no tokens in the collection — returns empty list
- Ethereum node latency or RPC unavailability — timeout or error response
- Payment not settled via x402 — access denied

## Output

A list of ERC-721 token IDs currently held by the specified owner address within the given ERC-721 contract on Ethereum mainnet, read from the latest block. The response reflects the current on-chain state via the contract's Enumerable extension.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "owner": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "0x + 40 hex"
      },
      "token": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "ERC-721 contract (Enumerable), 0x + 40 hex"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ethereum-erc-721-token-ids-by-owner-e9e98ed2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.arysphere.com](https://www.zero.xyz/host/api.arysphere.com/llms.txt)