# Biosfera Storage Slot Reader

> Biosfera Storage Slot Reader is a paid API for AI agents from biosfera.46-62-215-147.sslip.io, paid per call via x402, $0.001/call, status down (last checked 2026-10-02).

Returns the raw 32-byte value stored at a specific storage slot of a smart contract on Base, Ethereum, Arbitrum, Optimism, or Polygon using eth_getStorageAt

## Facts

- Endpoint: GET https://biosfera.46-62-215-147.sslip.io/o/storage-slot?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: down
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/biosfera-storage-slot-reader-580cc76d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_g3jYzEKs7zi7guQkioSkK

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 biosfera-storage-slot-reader-580cc76d
```

Example prompt: What's the raw value stored at storage slot 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc of contract 0x1234567890abcdef1234567890abcdef12345678 on Ethereum? I need to check the EIP-1967 implementation address.

## When to prefer this

Use this endpoint when you need low-level, raw storage access to an EVM smart contract — especially for inspecting proxy patterns (EIP-1967, EIP-1822), reading packed state variables, or verifying ownership slots directly without relying on ABI-decoded contract calls. Prefer this over higher-level token or balance endpoints when you need arbitrary slot data not exposed by standard ERC interfaces. Covers Base, Ethereum, Arbitrum, Optimism, and Polygon.

## Known failure modes

- Invalid contract address format (not a 40-hex-char 0x address) returns a validation error
- Invalid slot format (not a valid hex or decimal number) returns a validation error
- Unsupported chain name returns an enum validation error
- Contract address that does not exist on the chain returns 0x0000...0000 (empty slot, not an error)
- Network RPC timeout or unavailability returns a service error
- Payment not provided or insufficient returns 402 Payment Required

## How this service works

Use when you need the raw 32-byte value of a storage slot of a contract on Base, Ethereum, Arbitrum, Optimism or Polygon via eth_getStorageAt, for example to inspect proxies, owners or packed state.

## Output

Returns the raw 32-byte hexadecimal value stored at the specified storage slot of the given contract on the requested chain, as returned by eth_getStorageAt. Useful for reading proxy pointers, owner addresses, packed bitfields, and any other low-level on-chain state.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "chain",
      "address",
      "slot"
     ],
     "properties": {
      "slot": {
       "type": "string",
       "pattern": "^(0x[0-9a-fA-F]{1,64}|[0-9]{1,20})$"
      },
      "chain": {
       "enum": [
        "base",
        "ethereum",
        "arbitrum",
        "optimism",
        "polygon"
       ],
       "type": "string"
      },
      "address": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$"
      }
     },
     "additionalProperties": false
    }
   },
   "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/biosfera-storage-slot-reader-580cc76d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from biosfera.46-62-215-147.sslip.io](https://www.zero.xyz/host/biosfera.46-62-215-147.sslip.io/llms.txt)