# Base Contract Raw Storage Slot Reader (eth_getStorageAt)

> Base Contract Raw Storage Slot Reader (eth_getStorageAt) is a paid API for AI agents from x402-data-api.sigrunner.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).

Returns the raw 32-byte storage slot value for any Base contract address using eth_getStorageAt, ideal for reading proxy implementation/admin slots or arbitrary contract state.

## Facts

- Endpoint: GET https://x402-data-api.sigrunner.workers.dev/chain/storage-at?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-24
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-contract-raw-storage-slot-reader-eth-getstorageat-ce9d9c88
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Qgeao-VxqcyrYVVS9Nitp

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-contract-raw-storage-slot-reader-eth-getstorageat-ce9d9c88
```

Example prompt: What is the raw value stored at storage slot 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc on Base contract 0x833589fCd6eDb6E08f4c7C32D4f71b54bdA02913? That's the EIP-1967 implementation slot — I want to see what address it points to.

## When to prefer this

Use this endpoint when an agent needs low-level on-chain storage inspection for Base contracts — particularly for reading EIP-1967 proxy implementation/admin slots, verifying upgrade state, or accessing raw storage values that are not exposed through ABI-decoded read functions. Prefer this over higher-level contract-call endpoints when you need to bypass ABI decoding or when the slot layout is known but no public getter exists. At $0.002 per call it is cost-effective for single-slot spot checks.

## Known failure modes

- Invalid or non-0x-prefixed contract address returns an error response
- Non-existent contract or EOA address returns a zero value (0x000...0000) without indicating absence of contract
- Invalid slot hex format may cause a bad request error
- Network or RPC connectivity issues on Base may result in a 5xx response
- Payment failure via x402 protocol (insufficient USDC) blocks the request before it reaches the RPC

## How this service works

Raw storage slot (eth_getStorageAt) of a Base contract. Use when an agent needs proxy implementation/admin slots or raw contract state.

## Output

Returns a JSON object with four fields: address (the queried contract), slot (the hex slot index), value (the 32-byte hex-encoded storage value), and chain (always 'base'). The value can be decoded as an address, uint256, bool, or bytes32 depending on the contract's storage layout.

## 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",
     "properties": {
      "slot": {
       "type": "string",
       "description": "storage slot hex, default 0x0"
      },
      "address": {
       "type": "string",
       "description": "0x-prefixed contract address on Base"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "address",
      "slot",
      "value",
      "chain"
     ],
     "properties": {
      "slot": {
       "type": "string"
      },
      "chain": {
       "type": "string"
      },
      "value": {
       "type": "string"
      },
      "address": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "slot": "0x0",
  "chain": "base",
  "value": "0x0000000000000000000000000000000000000000000000000000000000000001",
  "address": "0x833589fCd6eDb6E08f4c7C32D4f71b54bdA02913"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-contract-raw-storage-slot-reader-eth-getstorageat-ce9d9c88/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-data-api.sigrunner.workers.dev](https://www.zero.xyz/host/x402-data-api.sigrunner.workers.dev/llms.txt)