FabTally Decode

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io.github.zvmzaretsky/onchain-decodev1.0.0

Decode EVM bytes to JSON: event-log decoder, calldata explainer, selector lookup, ABI fetch.

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abi_fetch

PAID $0.002 (x402, USDC on Base). Fetch the verified ABI + metadata for a contract. Give {address, chain}; get the ABI JSON, verification status/source (Sourcify or Blockscout), the callable function/event signatures, and full proxy-implementation resolution (EIP-1967/1822/OZ-legacy/beacon) — returning the implementation's ABI when it's a proxy. Without payment returns the x402 challenge; pass x_payment to settle.

chainstring, required

addressstring, required

Contract address (0x + 40 hex).

x_paymentstring

x402 payment payload (base64) for this PAID decode. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first.

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Tools (4)

abi_fetch

Argument	Type	Description
chain*	string	EVM chain: ethereum \| base \| arbitrum \| optimism \| polygon \| bsc.
address*	string	Contract address (0x + 40 hex).
x_payment	string	x402 payment payload (base64) for this PAID decode. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first.

Input schema (JSON)

{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "required": [
    "chain",
    "address"
  ],
  "properties": {
    "chain": {
      "enum": [
        "ethereum",
        "base",
        "arbitrum",
        "optimism",
        "polygon",
        "bsc"
      ],
      "type": "string",
      "description": "EVM chain: ethereum | base | arbitrum | optimism | polygon | bsc."
    },
    "address": {
      "type": "string",
      "description": "Contract address (0x + 40 hex)."
    },
    "x_payment": {
      "type": "string",
      "description": "x402 payment payload (base64) for this PAID decode. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first."
    }
  },
  "additionalProperties": false
}

decode_calldata

PAID $0.002 (x402, USDC on Base). Decode a contract function call. Give {chain, to?, data, abi?}; get the 4-byte selector resolved to a function signature (via provided ABI, the verified contract source, or 4byte.directory) plus fully decoded, typed arguments (tuples/arrays/nested included). Without payment returns the x402 challenge.

Argument	Type	Description
to	string	Contract address the call targets (optional; enables verified-ABI resolution).
abi	any	Optional contract ABI (JSON array or JSON string). If omitted, the ABI is resolved from the verified source (Sourcify/Blockscout) or 4byte.directory.
data*	string	Calldata (0x hex, at least the 4-byte selector).
chain*	string	EVM chain: ethereum \| base \| arbitrum \| optimism \| polygon \| bsc.
x_payment	string	x402 payment payload (base64) for this PAID decode. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first.

Input schema (JSON)

{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "required": [
    "chain",
    "data"
  ],
  "properties": {
    "to": {
      "type": "string",
      "description": "Contract address the call targets (optional; enables verified-ABI resolution)."
    },
    "abi": {
      "anyOf": [
        {
          "type": "array"
        },
        {
          "type": "string"
        }
      ],
      "description": "Optional contract ABI (JSON array or JSON string). If omitted, the ABI is resolved from the verified source (Sourcify/Blockscout) or 4byte.directory."
    },
    "data": {
      "type": "string",
      "description": "Calldata (0x hex, at least the 4-byte selector)."
    },
    "chain": {
      "enum": [
        "ethereum",
        "base",
        "arbitrum",
        "optimism",
        "polygon",
        "bsc"
      ],
      "type": "string",
      "description": "EVM chain: ethereum | base | arbitrum | optimism | polygon | bsc."
    },
    "x_payment": {
      "type": "string",
      "description": "x402 payment payload (base64) for this PAID decode. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first."
    }
  },
  "additionalProperties": false
}

decode_log

PAID $0.003 (x402, USDC on Base). FLAGSHIP: decode EVM event LOGS to human-readable JSON. Give {chain, tx_hash} to decode every log in a transaction, OR {chain, address, topics[], data} for a single log; optional {abi}. Returns each event's name, canonical signature and named/typed args — correctly handling tuple/array/nested params, anonymous events, and indexed vs non-indexed. Resolves the ABI via Sourcify/Blockscout + 4byte event signatures when none is supplied. Without payment returns the x402 challenge; pass x_payment to settle.

Argument	Type	Description
abi	any	Optional contract ABI (JSON array or JSON string). If omitted, the ABI is resolved from the verified source (Sourcify/Blockscout) or 4byte.directory.
data	string	Log data field (0x hex) holding the non-indexed args.
chain*	string	EVM chain: ethereum \| base \| arbitrum \| optimism \| polygon \| bsc.
topics	array	Log topics array (topic0 is the event signature hash for non-anonymous events).
address	string	Contract address of a single log (used with topics + data).
tx_hash	string	Transaction hash (0x + 64 hex) — decodes every event log in the tx.
x_payment	string	x402 payment payload (base64) for this PAID decode. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first.

selector_lookup

PAID $0.001 (x402, USDC on Base). Resolve a 4-byte function selector (0x + 8 hex) OR a 32-byte event topic hash (0x + 64 hex) to its human-readable signature(s) via 4byte.directory + openchain.xyz. Returns all matches (selectors can collide) with a verified flag. Without payment returns the x402 challenge; pass x_payment to settle.

Argument	Type	Description
selector*	string	A 4-byte function selector (0x + 8 hex) or a 32-byte event topic hash (0x + 64 hex).
x_payment	string	x402 payment payload (base64) for this PAID decode. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first.

Input schema (JSON)

{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "required": [
    "selector"
  ],
  "properties": {
    "selector": {
      "type": "string",
      "description": "A 4-byte function selector (0x + 8 hex) or a 32-byte event topic hash (0x + 64 hex)."
    },
    "x_payment": {
      "type": "string",
      "description": "x402 payment payload (base64) for this PAID decode. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first."
    }
  },
  "additionalProperties": false
}