# Xerxes ERC-20 Token Balance (Ethereum Mainnet)

> Xerxes ERC-20 Token Balance (Ethereum Mainnet) is a paid API for AI agents from ari001.tailb4ac3a.ts.net, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-02).

Returns the live ERC-20 token balance of any Ethereum address by calling balanceOf on the token contract at the latest block, expressed as a raw uint256 decimal string.

## Facts

- Endpoint: GET https://ari001.tailb4ac3a.ts.net/v1/ventures/ethereum_rpc_api/erc20_balance?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/xerxes-erc-20-token-balance-ethereum-mainnet-2294f04a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__mhWg9Jsp4TK9-sr_kWAv

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 xerxes-erc-20-token-balance-ethereum-mainnet-2294f04a
```

Example prompt: What's the current USDC balance (contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48) held by the wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Ethereum mainnet right now?

## When to prefer this

Use this endpoint when you need the live, current ERC-20 token balance of a specific address on Ethereum mainnet and require the raw uint256 value (e.g. for precise arithmetic before displaying human-readable amounts). Prefer it over block-explorer scraping (which is brittle) or general-purpose RPC libraries (which require setup) when you need a fast, single read-only call with no infrastructure overhead. For Base network ERC-20 balances, use the sibling Base balance endpoint instead.

## Known failure modes

- Invalid token or address format (not matching 0x + 40 hex) — request rejected before RPC call
- Token contract address is not a valid ERC-20 (balanceOf not implemented) — RPC call reverts or returns unexpected data
- Address has no balance — returns ok:true with result '0'
- Ethereum node connectivity issues — may return an error with ok:false
- Rate limiting or payment issues — HTTP 402 or 429 response

## How this service works

ERC-20 token balance of any address on Ethereum mainnet, read live via balanceOf (eth_call) at the latest block. Returns the raw integer balance in the token's smallest unit. Query: token (ERC-20 contract, 0x + 40 hex), address (holder, 0x + 40 hex).

## Output

Returns a JSON object with ok (boolean), result (the uint256 balance as a decimal string in the token's smallest unit, e.g. 6 decimals for USDC), chain (e.g. 'ethereum'), method ('balanceOf'), and service name. On error, ok is false and an error field is present instead of result.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "token",
      "address"
     ],
     "properties": {
      "token": {
       "type": "string",
       "pattern": "^0x[a-fA-F0-9]{40}$",
       "description": "ERC-20 contract, 0x + 40 hex"
      },
      "address": {
       "type": "string",
       "pattern": "^0x[a-fA-F0-9]{40}$",
       "description": "holder, 0x + 40 hex"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "ok",
      "service"
     ],
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "chain": {
       "type": "string"
      },
      "error": {
       "type": "string",
       "description": "present when ok is false"
      },
      "method": {
       "type": "string"
      },
      "result": {
       "type": "string",
       "description": "the uint256 as a decimal string"
      },
      "service": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/xerxes-erc-20-token-balance-ethereum-mainnet-2294f04a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ari001.tailb4ac3a.ts.net](https://www.zero.xyz/host/ari001.tailb4ac3a.ts.net/llms.txt)