# HALOWERK kettenwerk Contract Verification Checker

> HALOWERK kettenwerk Contract Verification Checker is a paid API for AI agents from kette.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-13).

Checks whether a smart contract (and its implementation, if it's a proxy) is source-verified on Ethereum, Base, Arbitrum, Optimism, Polygon, or BNB Smart Chain

## Facts

- Endpoint: POST https://kette.halowerk.com/contract/verification?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-kettenwerk-contract-verification-checker-c1d75b84
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8pEJAmEtJOL1iZ1qBTY0W

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 halowerk-kettenwerk-contract-verification-checker-c1d75b84 -d '<json body>'
```

Example prompt: Check whether the contract at 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on Ethereum is source-verified, and if it's a proxy, tell me whether the implementation it points to is also verified.

## When to prefer this

Use this endpoint when you need to determine whether a smart contract's source code is publicly verified before interacting with it, auditing it, or presenting it to a user. It is especially valuable for proxy contracts, where the surface-level proxy may be verified while the actual logic implementation is not — a distinction most generic block explorer lookups miss. Prefer this over manual Etherscan lookups when operating across multiple EVM chains (Ethereum, Base, Arbitrum, Optimism, Polygon, BSC) and when proxy-awareness (EIP-1967, EIP-1167, implementation() call) is required.

## Known failure modes

- Invalid or non-checksummed address format returns a validation error
- Unsupported chain enum value returns an error
- Contract does not exist at the given address on the specified chain
- Proxy pattern not recognized — implementation address cannot be resolved
- Block explorer or RPC temporarily unavailable — verification registry unreachable
- Network timeout when reading EIP-1967 storage slot or calling implementation()

## How this service works

Checks one address on Ethereum, Base, Arbitrum, Optimism, Polygon or BNB Smart Chain against the open verification registry and against the chain itself. For a proxy the answer is deliberately split in two: whether the proxy is verified says almost nothing, whether the implementation it currently points to is verified is the real question, and both are reported separately with the implementation address read from the EIP-1967 storage slot, the EIP-1167 clone pattern or an implementation() call —

## Output

Returns two separate verification statuses: one for the contract address itself (is it verified in the open registry?), and one for the implementation it currently points to if the contract is a proxy — resolved via EIP-1967 storage slot, EIP-1167 clone detection, or an implementation() call. The implementation address is also returned. This split answer allows the caller to understand whether the meaningful code layer (the implementation) is inspectable, not just the proxy shell.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "chain": {
   "enum": [
    "ethereum",
    "base",
    "arbitrum",
    "optimism",
    "polygon",
    "bsc"
   ],
   "type": "string",
   "description": "Chain the contract lives on."
  },
  "address": {
   "type": "string",
   "pattern": "^0x[0-9a-fA-F]{40}$",
   "description": "Contract address."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-kettenwerk-contract-verification-checker-c1d75b84/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from kette.halowerk.com](https://www.zero.xyz/host/kette.halowerk.com/llms.txt)