# Proxy Contract Detector & Implementation Resolver

> Proxy Contract Detector & Implementation Resolver is a paid API for AI agents from api.x402node.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Detects whether an Ethereum or Base contract is an upgradeable proxy and resolves its current implementation address by reading EIP-1967/EIP-1822 storage slots on-chain.

## Facts

- Endpoint: GET https://api.x402node.dev/chain/proxy-detect
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/proxy-contract-detector-implementation-resolver-fb2c1bfa
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_NSb9TvuFNMWaxXuS6PAyb

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 proxy-contract-detector-implementation-resolver-fb2c1bfa
```

Example prompt: Can you check if the contract at 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on Ethereum is an upgradeable proxy, and if so, what's the current implementation address it points to?

## When to prefer this

Use this endpoint when you need to determine whether a smart contract is an upgradeable proxy and identify its underlying implementation address — particularly when you cannot read on-chain storage yourself (e.g., LLMs or agents without direct RPC access). Prefer this over generic block explorers when you need a structured, programmatic answer about EIP-1967 or EIP-1822 proxy patterns on Ethereum or Base.

## Known failure modes

- Contract address is not a valid Ethereum address — returns 400 or validation error
- Contract is not deployed on the specified chain — returns empty or null implementation
- Network is unavailable or RPC node is unresponsive — returns 500 or timeout
- Contract exists but uses a non-standard or custom proxy pattern not covered by EIP-1967/1822 — returns proxy=false even though it may be a proxy
- Invalid or unsupported chain specified — returns 400

## How this service works

Detect whether a contract is an upgradeable proxy and resolve its implementation address by reading EIP-1967/1822 storage slots on Ethereum or Base - on-chain state LLMs cannot access. proxy detect, proxy contract, implementation address, upgradeable proxy, eip1967, proxy resolver

## Output

Returns whether the contract is a proxy, the detected proxy standard (EIP-1967 or EIP-1822), the resolved implementation contract address, and the raw storage slot values read from the chain.

## Example request

```json
{
 "chain": "ethereum",
 "address": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"
}
```

## 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": {
      "chain": {
       "type": "string",
       "description": "ethereum, base (default)"
      },
      "address": {
       "type": "string",
       "description": "Contract address (required)"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/proxy-contract-detector-implementation-resolver-fb2c1bfa/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.x402node.dev](https://www.zero.xyz/host/api.x402node.dev/llms.txt)