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Delx EVM Calldata Selector Extract
x402
Delx EVM Calldata Selector Extract is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).
Extracts the 4-byte function selector from raw EVM transaction calldata and validates its shape.
Price / call$0.001
Success—
StatusUnknown
How this service works
EVM Calldata Selector Extract: EVM Calldata Selector Extract extracts the first four calldata bytes as a selector from bounded caller-supplied values without an external provider. Call EVM Calldata Selector Extract before signing, submitting, replacing, or accepting an EVM/Base transaction assembled from caller-owned data. Returns normalized transaction evidence, calculated budget or shape findings, and a fail-closed preflight status for EVM Calldata Selector Extract as versioned deterministic…
Output
Returns the original calldata, the extracted 4-byte function selector (e.g. 0xa9059cbb), total byte count, a boolean shape_valid flag indicating whether the calldata is properly formed, plus evidence fields including whether input was retained (always false), the SHA-256 hash of the input, and external call count (always 0).
Example use cases
Pre-flight check before contract call
“Before I submit this transaction, parse the calldata 0xa9059cbb000000000000000000000000abcdef1234567890abcdef1234567890abcdef12000000000000000000000000000000000000000000000000016345785d8a0000 and tell me the function selector and whether the format looks valid.”
Identify function being invoked
“I have this raw hex calldata from a pending Ethereum transaction: 0x23b872dd000000000000000000000000abc... — what function selector does it start with and how many bytes is the calldata total?”
Validate calldata shape for agent pipeline
“Check if this EVM calldata 0x095ea7b30000000000000000000000001234567890abcdef1234567890abcdef12345678ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff is well-formed and extract its 4-byte selector so I can route it correctly.”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/evm-calldata-selector-extractWhen to prefer
Use this endpoint when an AI agent needs to inspect or validate raw EVM calldata before executing or routing a smart contract transaction, especially during preflight checks in automated blockchain workflows. Prefer this over manual parsing when you need a verifiable, auditable result with SHA-256 evidence and no data retention guarantees.
Side effects
- Invalid or non-hex calldata string returns a failed parse result
- Calldata shorter than 4 bytes may result in shape_valid: false
- Input exceeding 8192 character limit may be rejected
- Malformed JSON request body returns HTTP 400
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| calldata | string | Calldata supplied to EVM Calldata Selector Extract; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"calldata": "0xa9059cbb0000000000000000000000001111111111111111111111111111111111111111",
"selector": "0xa9059cbb",
"byte_count": 36,
"shape_valid": true
},
"schema": "delx/util-evm-calldata-selector-extract/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "1048e8d74a53c6ea3249086735deac2cb24ee3dd131a3852df0439253301d8de",
"external_calls": 0
},
"operation": "evm_preflight:evm_calldata_selector_extract"
}
}Tags
x402
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