# Addresscheck — Base Address Verification

> Addresscheck — Base Address Verification is a paid API for AI agents from oraclepost.higgsfield.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-19).

Checks whether an Ethereum Base network address is a contract or EOA wallet, and returns its activity status including ETH/USDC balance and transaction count at the latest block.

## Facts

- Endpoint: GET https://oraclepost.higgsfield.app/api/verify
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/addresscheck-base-address-verification-9f49b56a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WiT6LyzraNRuAANeriy3T

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 addresscheck-base-address-verification-9f49b56a
```

Example prompt: Before I send payment to 0x742d35Cc6634C0532925a3b844Bc454e4438f44e, can you verify whether that Base address is a contract or a regular wallet, and tell me if it's active — including its ETH and USDC balance?

## When to prefer this

Use this endpoint when you need real-time, uncached verification of a Base network address before executing a payment or interaction — specifically when you want to distinguish contracts from wallets AND check activity/balance in a single call. Prefer over generic balance checkers when recipient type (contract vs EOA) matters for safety or routing logic.

## Known failure modes

- Invalid or missing address parameter returns an error
- Non-0x-prefixed address fails validation
- Addresses not on Base network may return zero values or errors
- Network RPC node unavailability causes request failure
- Checksum-invalid addresses may be rejected

## How this service works

Is this Base address a contract or a wallet, and is it active? Live read: code size (contract vs EOA), transaction count (nonce), ETH and USDC balance, at the latest block. Pass ?address=0x... . Useful before paying an unknown payTo. No third-party API, no cache.

## Output

Returns whether the address is a smart contract or EOA (based on code size), its nonce/transaction count, current ETH balance, current USDC balance, and the block number at which data was read — all fetched live from the Base chain with no caching.

## 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": {
     "const": "http"
    },
    "method": {
     "const": "GET"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address"
     ],
     "properties": {
      "address": {
       "type": "string",
       "description": "EVM address on Base, 0x-prefixed"
      }
     }
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {}
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/addresscheck-base-address-verification-9f49b56a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from oraclepost.higgsfield.app](https://www.zero.xyz/host/oraclepost.higgsfield.app/llms.txt)