# Base Is-Contract Checker

> Base Is-Contract Checker is a paid API for AI agents from agent-data-tools.revmesh2074.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-19).

Checks whether a given 0x address on the Base blockchain is a smart contract or an externally-owned account (EOA), and returns contract metadata including code size, minimal proxy detection, and implementation address.

## Facts

- Endpoint: GET https://agent-data-tools.revmesh2074.workers.dev/base/is-contract?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-is-contract-checker-2e59f779
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_oLaKQcAqya96rB29LbkWQ

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 base-is-contract-checker-2e59f779
```

Example prompt: Can you check if 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 is a smart contract or a regular wallet on Base, and tell me if it's a proxy?

## When to prefer this

Use this endpoint when you specifically need to classify a Base-chain address as contract vs EOA, detect minimal proxy patterns, or retrieve code size — especially in DeFi, security, or compliance workflows where knowing whether an address holds executable code matters. Prefer this over generic Ethereum tools when the target chain is Base (chainId 8453).

## Known failure modes

- Invalid or malformed 0x address returns an error
- Address not found on Base (e.g. address never deployed) returns isContract: false
- Network/RPC errors on Base may cause transient failures (not charged on failure)
- Non-checksummed addresses may cause validation errors

## How this service works

Check whether a 0x address on Base is a smart contract or a plain wallet: bytecode size, and whether it is an EIP-1167 minimal proxy and which implementation it points to. Use before sending funds or approving a spender; for a fuller risk verdict use check_counterparty. A malformed address is rejected with 400, uncharged.

## Output

Returns a JSON object with: chain name ('Base'), chainId (8453), the queried address, codeBytes (number of bytecode bytes at the address), isContract (true/false boolean), minimalProxy (true/false indicating EIP-1167 minimal proxy pattern), and implementation (the logic contract address if it's a proxy, or null).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address"
     ],
     "properties": {
      "address": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "examples": [
        "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
       ],
       "description": "0x address"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "chain": {
       "type": "string"
      },
      "address": {
       "type": "string"
      },
      "chainId": {
       "type": "number"
      },
      "codeBytes": {
       "type": "number"
      },
      "isContract": {
       "type": "boolean"
      },
      "minimalProxy": {
       "type": "boolean"
      },
      "implementation": {}
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "chain": "Base",
  "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
  "chainId": 8453,
  "codeBytes": 1855,
  "isContract": true,
  "minimalProxy": false,
  "implementation": null
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-is-contract-checker-2e59f779/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-data-tools.revmesh2074.workers.dev](https://www.zero.xyz/host/agent-data-tools.revmesh2074.workers.dev/llms.txt)