# Contract Storage Slot Reader

> Contract Storage Slot Reader is a paid API for AI agents from bess-x402.onrender.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-30).

Reads a raw EVM contract storage slot via eth_getStorageAt and returns the value decoded as hex, uint256, and address.

## Facts

- Endpoint: GET https://bess-x402.onrender.com/v1/evm/storage?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/contract-storage-slot-reader-7b2882bc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ohEsU-Elpa6Doxz5qPV8f

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 contract-storage-slot-reader-7b2882bc
```

Example prompt: What's stored in slot 0 of the contract at 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on Ethereum — show me the raw hex, the uint256, and what address it decodes to.

## When to prefer this

Use this endpoint when you need to inspect low-level EVM storage of any contract — especially for reading proxy implementation slots (EIP-1967, EIP-1822), admin slots, or packed variables that aren't exposed via ABI. Prefer it over event logs or decoded ABI calls when you need raw on-chain state verification or debugging. Supports Ethereum, Base, Arbitrum, Optimism, and Polygon.

## Known failure modes

- Invalid contract address format returns a 400 error
- Non-existent slot returns a zero value (not an error)
- Unsupported chain name returns a 400 or 422 error
- Invalid block number or tag returns an error
- Node RPC timeout causes a 503 or 504 response
- Payment not received results in 402 Payment Required

## How this service works

Read a raw storage slot of any contract (eth_getStorageAt), also decoded as uint and address. Use for proxy slots, packed variables and debugging.

## Output

Returns the 32-byte raw hex value of the requested storage slot, along with two decoded interpretations: the value as a uint256 integer and as a checksummed Ethereum address (useful for proxy implementation or admin slots). Also echoes back the contract address, slot, chain, and block reference.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address",
      "slot"
     ],
     "properties": {
      "slot": {
       "type": "string",
       "description": "Slot as decimal or 0x hex"
      },
      "block": {
       "type": "string",
       "description": "Block number or latest"
      },
      "chain": {
       "type": "string",
       "description": "ethereum, base, arbitrum, optimism or polygon"
      },
      "address": {
       "type": "string",
       "description": "Contract address"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/contract-storage-slot-reader-7b2882bc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bess-x402.onrender.com](https://www.zero.xyz/host/bess-x402.onrender.com/llms.txt)