---
name: chainstate
description: One-call Base address profile for agents: code, proxy, interfaces, token, balances, denylist.
---

# ChainState

ChainState answers everything an agent needs to know about a Base address before interacting with it, in one paid call rather than four to six a-la-carte lookups. It reports whether the address holds code and how much, resolves proxies across all seven known slot layouts — including the legacy OpenZeppelin slot that Base USDC really uses, which an EIP-1967-only detector misses entirely — and returns the implementation behind the indirection, ERC-165 interface support, behavioural ERC-20 detection, token metadata, and the balances you asked for. There is no model anywhere in it. A contract that does not answer supportsInterface is reported as null, never false, and there is deliberately no reverse-name field: a name the subject can set for itself, published without a forward check, would be the one spoofable value in the response.

## When to use this

Use `POST https://chainstate.schemasure.com/v1/chain/state` when you need: Profile a Base address: code, proxy, interfaces, token metadata, balances, denylist.

## How to pay

1. Send the request without payment. You receive HTTP 402 and a base64 `PAYMENT-REQUIRED` header.
2. Decode it, sign one of the `accepts` entries with your wallet locally.
3. Retry the identical request with the `PAYMENT-SIGNATURE` header.
4. A successful response carries a `PAYMENT-RESPONSE` receipt.

Cost: $0.01 in USDC on Base mainnet. Failed calls are free.
Your private key never leaves your process.

## Request

```json
{
  "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
}
```

## Response

```json
{
  "ok": true,
  "verdict": "warn",
  "confidence": 1,
  "risk_codes": [
    "PROXY_UPGRADEABLE"
  ],
  "evidence": [
    {
      "code": "INTERFACE_PROBE_UNANSWERED",
      "severity": "info",
      "detail": "This contract did not answer supportsInterface, so ERC-721 and ERC-1155 support is reported as null. That is not evidence against them: plenty of live contracts predate ERC-165 entirely.",
      "source": "erc165"
    },
    {
      "code": "PROXY_UPGRADEABLE",
      "severity": "medium",
      "detail": "This is an upgradeable zeppelinos proxy. Everything reported here describes the implementation deployed right now; the admin can point it elsewhere before your next call lands, so this is a risk signal rather than metadata.",
      "source": "proxy-slots",
      "data": {
        "kind": "zeppelinos",
        "implementation": "0x2Ce6311ddAE708829bc0784C967b7d77D19FD779",
        "admin": "0x4fc7850364958d97B4d3f5A08f79db2493f8cA44"
      }
    }
  ],
  "result": {
    "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "chain": "eip155:8453",
    "account": {
      "is_contract": true,
      "code_size": 1852,
      "detail": "1852 bytes of runtime code"
    },
    "proxy": {
      "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "kind": "zeppelinos",
      "implementation": "0x2Ce6311ddAE708829bc0784C967b7d77D19FD779",
      "admin": "0x4fc7850364958d97B4d3f5A08f79db2493f8cA44",
      "beacon": null,
      "upgradeable": true,
      "slots_probed": [
        {
          "slot": "0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc",
          "label": "eip1967.implementation",
          "value": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "address": null
        },
        {
          "slot": "0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103",
          "label": "eip1967.admin",
          "value": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "address": null
        },
        {
          "slot": "0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50",
          "label": "eip1967.beacon",
          "value": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "address": null
        },
        {
          "slot": "0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7",
          "label": "eip1822.uups",
          "value": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "address": null
        },
        {
          "slot": "0x7050c9e0f4ca769c69bd3a8ef740bc37934f8e2c036e5a723fd8ee048ed3f8c3",
          "label": "zeppelinos.implementation",
          "value": "0x0000000000000000000000002ce6311ddae708829bc0784c967b7d77d19fd779",
          "address": "0x2Ce6311ddAE708829bc0784C967b7d77D19FD779"
        },
        {
          "slot": "0x10d6a54a4754c8869d6886b5f5d7fbfa5b4522237ea5c60d11bc4e7a1ff9390b",
          "label": "zeppelinos.admin",
          "value": "0x0000000000000000000000004fc7850364958d97b4d3f5a08f79db2493f8ca44",
          "address": "0x4fc7850364958d97B4d3f5A08f79db2493f8cA44"
        },
        {
          "slot": "0xc8fcad8db84d3cc18b4c41d551ea0ee66dd599cde068d998e57d5e09332c131c",
          "label": "eip2535.diamond",
          "value": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "address": null
        }
      ],
      "detail": "resolved through the legacy zeppelinos slot; the EIP-1967 slot is empty on this contract, which is the case for Base USDC"
    },
    "interfaces": {
      "erc165": null,
      "erc721": null,
      "erc1155": null,
      "erc20": true,
      "detail": "supportsInterface did not answer, so ERC-721 and ERC-1155 are reported as unknown rather than absent; ERC-20 is confirmed behaviourally from totalSupply, decimals, and balanceOf"
    },
    "token": {
      "symbol": "USDC",
      "decimals": 6,
      "total_supply": "4305008625389354",
      "detail": "symbol, decimals, and totalSupply read from the token"
    },
    "balances": [],
    "denylist_hits": [],
    "unresolved": [
      "ERC-165 interface support: supportsInterface did not answer"
    ],
    "rpc": {
      "configured": true,
      "reachable": true,
      "endpoints": [
        {
          "url": "https://mainnet.base.org",
          "latest": true,
          "archive": true,
          "simulate": true
        }
      ]
    }
  },
  "policy_version": "2026-09-19",
  "request_hash": "sha256:96b41fa639c553a6dc6bfaa1d8ccc056912abc36e8bbde3d65f3e1edc2bd147f",
  "data_versions": {
    "denylist": "2026-08-03.1",
    "abi_packs": "2026-08-03.1",
    "proxy_slots": "7",
    "policy": "2026-09-19",
    "chain": "eip155:8453"
  },
  "warnings": []
}
```

## Reading the verdict

- `resolved` / `pass` / `allow` — the service answered and the answer is usable.
- `warn` — usable, but `evidence` contains findings you should act on.
- `block` — the service is telling you not to proceed. Read `risk_codes`.
- `unknown` — the service could not determine the answer. **Do not treat this as safe.**