# Quartermaster Base Contract Checker

> Quartermaster Base Contract Checker is a paid API for AI agents from quartermaster.surewhynot.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Determines whether a given Base blockchain address is a smart contract or an externally-owned account (EOA).

## Facts

- Endpoint: GET https://quartermaster.surewhynot.app/v1/base/contract
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quartermaster-base-contract-checker-add542a6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_orh2VTf140Ux4t-_2T3Pj

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 quartermaster-base-contract-checker-add542a6
```

Example prompt: Is the Base address 0x4200000000000000000000000000000000000006 a smart contract or a regular wallet account?

## When to prefer this

Use this endpoint when you need to programmatically determine whether a Base blockchain address belongs to a smart contract or a human-controlled wallet, especially before sending transactions, validating token addresses, or filtering contract interactions from user wallets.

## Known failure modes

- Invalid address format (not a 0x-prefixed 40-character hex string) returns validation error
- Address not found or network unavailable returns error
- Rate limiting or payment failure returns 402 response

## How this service works

Determine whether a Base address is a contract or an externally-owned account.

## Output

Returns a classification indicating whether the provided Base address is a smart contract or an externally-owned account (EOA), helping agents distinguish between wallet addresses and deployed contract addresses.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address"
     ],
     "properties": {
      "address": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$"
      }
     }
    }
   },
   "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/quartermaster-base-contract-checker-add542a6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from quartermaster.surewhynot.app](https://www.zero.xyz/host/quartermaster.surewhynot.app/llms.txt)