{"uid":"cap_SVKeRY2N0zc4Z74ewB9aP","slug":"evm-storage-slot-hash-calculator-dcca49a4","name":"EVM Storage Slot Hash Calculator","description":"Compute the exact EVM storage slot hash keccak256(abi.encode(key, slot)) for a Solidity mapping entry.","url":"https://bot-bazaar.fly.dev/v1/x402/storage-slot-calc?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"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"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.01","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_QIitJDHT9rtAxxO7ytDyC","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the exact EVM storage slot hash keccak256(abi.encode(key, slot)) for a Solidity mapping entry given a mapping key.","exampleAgentPrompt":"Calculate the EVM storage slot hash for mapping key address 0xAbC1234567890000000000000000000000000001 at slot index 2 using keccak256(abi.encode(key, slot)).","exampleUseCases":[{"title":"Inspect live contract storage value","prompt":"I need the exact storage slot hash for address 0xDEADBEEF000000000000000000000000deadbeef at slot 0 in a Solidity mapping so I can call eth_getStorageAt and read the raw value from the contract."},{"title":"Debug Solidity mapping storage layout","prompt":"My smart contract has a balances mapping at slot 3 — can you compute the storage slot hash for key 0x1111111111111111111111111111111111111111 so I can verify the value is stored at the right location?"},{"title":"Automate storage proof verification","prompt":"I'm building a storage proof and need the keccak256 abi.encode hash for mapping key 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa at slot index 5 — what's the resulting storage slot?"}],"resultDescription":"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.","failureModes":["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"],"whenToPreferThis":"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.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-31T18:40:40.560Z","isFirstParty":false,"canonicalSlug":"evm-storage-slot-hash-calculator-dcca49a4"}