# EVM Storage Slot Hash Calculator

> EVM Storage Slot Hash Calculator is a paid API for AI agents from bot-bazaar.fly.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-31).

Computes the exact EVM storage slot hash keccak256(abi.encode(key, slot)) for a Solidity mapping entry given a mapping key.

## Facts

- Endpoint: GET https://bot-bazaar.fly.dev/v1/x402/storage-slot-calc?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evm-storage-slot-hash-calculator-dcca49a4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_SVKeRY2N0zc4Z74ewB9aP

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 evm-storage-slot-hash-calculator-dcca49a4
```

Example prompt: Calculate the EVM storage slot hash for mapping key address 0xAbC1234567890000000000000000000000000001 at slot index 2 using keccak256(abi.encode(key, slot)).

## When to prefer this

Use this endpoint when you need to deterministically compute the EVM storage slot for a Solidity mapping entry (keccak256(abi.encode(key, slot))) without running a local EVM or writing custom code. It is ideal for automating eth_getStorageAt lookups, building storage proofs, or debugging smart contract storage layouts.

## Known failure modes

- Missing or malformed mapping_key parameter returns an error
- Invalid hex format for key (not a valid address or 32-byte hex) causes a parsing error
- Missing slot index may result in a default or error depending on implementation
- Network or server errors from the fly.dev host may return 5xx responses
- Payment failure or invalid x402 payment header returns 402 Payment Required

## How this service works

Compute the exact EVM storage slot hash keccak256(abi.encode(key, slot)) for a Solidity mapping entry.

## Output

Returns the computed keccak256(abi.encode(key, slot)) hash representing the exact EVM storage slot where the mapping entry for the given key is stored, expressed as a 32-byte hex string.

## 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",
     "properties": {
      "mapping_key": {
       "type": "string",
       "description": "Mapping key address or 32-byte hex"
      }
     }
    }
   },
   "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/evm-storage-slot-hash-calculator-dcca49a4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bot-bazaar.fly.dev](https://www.zero.xyz/host/bot-bazaar.fly.dev/llms.txt)