{"uid":"cap_-5tDXrM-QGMgg3-Y9wOgy","slug":"solidity-abi-calldata-encoder-6e2b8a44","name":"Solidity ABI Calldata Encoder","description":"Solidity ABI calldata encoder — encode canonical typed values for an EVM smart-contract function call, with an optional selector and exact 256-bit integers.","url":"https://chain-tools.use.x402atlas.com/evm/abi-encode","method":"POST","headers":{},"bodySchema":null,"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"registry","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":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_7S82S4EA9W3ziPC4gqrqe","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":null,"unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Encodes canonical typed values into EVM smart-contract ABI calldata, optionally including a 4-byte function selector and exact 256-bit integers.","exampleAgentPrompt":"ABI-encode a call to transfer(address,uint256) on an EVM contract, passing recipient address 0xAbC1234567890abcdef1234567890abcdef123456 and exact uint256 amount 1000000000000000000, and include the 4-byte function selector in the output.","exampleUseCases":[{"title":"Encode raw ERC-20 transfer calldata","prompt":"ABI-encode a call to the ERC-20 transfer(address,uint256) function with recipient 0xDeAdBeEf00000000000000000000000000000001 and amount 500000000 as an exact uint256 — include the function selector so I can use this as raw calldata in a transaction."},{"title":"Prepare constructor args for contract deployment","prompt":"I need to ABI-encode constructor arguments for a Solidity contract deployment — the constructor is initialize(string,uint256,address) with values 'MyToken', 1000000 as exact uint256, and owner address 0x1234567890abcdef1234567890abcdef12345678, no selector needed."},{"title":"Build calldata for a multisig proposal","prompt":"Encode calldata for a governance proposal — the target function is setParams(uint256,bool,address) with values 42 as exact uint256, true, and 0xABCDEF1234567890ABcDEF1234567890abCDEF12, and include the 4-byte selector so the multisig can execute it directly."}],"resultDescription":"Returns a hex-encoded ABI calldata byte string conforming to the Solidity ABI specification. If a function selector is requested, the output is prefixed with the 4-byte keccak256-derived selector followed by the ABI-encoded parameters. Integers are encoded as exact 256-bit values padded to 32-byte slots.","failureModes":["Invalid or malformed Solidity type string causes encoding error","Type/value mismatch (e.g. passing a string where uint256 is expected) returns validation error","Malformed Ethereum address (wrong length or non-hex) rejected","Integer value exceeds 256-bit range returns overflow error","Missing required function signature when selector is requested","Unsupported or non-canonical Solidity type returns type-not-found error"],"whenToPreferThis":"Choose this endpoint when you need deterministic, canonical Solidity ABI encoding of typed values for EVM smart-contract calls — especially when you require exact 256-bit integer precision or an optional prepended 4-byte function selector. Prefer it over client-side encoding libraries when operating in a serverless or agent context without a Web3 runtime, or when you need a trusted third-party to produce verifiable calldata. The companion ABI decoder endpoint on the same platform handles the inverse operation.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T12:43:21.300Z","isFirstParty":false}