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EVM Signature V Classifier
x402
EVM Signature V Classifier 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).
Classifies an EVM transaction signature V value as legacy, EIP-155, or other type, given the V integer and chain ID.
Price / call$0.001
Success—
StatusUnknown
How this service works
EVM Signature V Classify: EVM Signature V Classify classifies common signature recovery and EIP-155 v values from bounded caller-supplied values without an external provider. Call EVM Signature V Classify 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 Signature V Classify as versioned deterministic JSON. Price: $0…
Output
Returns a JSON object containing the original V value, a classification string (e.g. 'legacy', 'eip155'), the expected chain ID derived from V, operation name, status ('pass'/'fail'), and an evidence block confirming no data was retained and no external calls were made.
Example use cases
Pre-flight signature validation for relay
“Before I broadcast this transaction on Base (chain ID 8453), can you classify the V value of 37 to confirm whether it's EIP-155 encoded or a legacy signature?”
Debugging raw transaction V field
“I'm parsing a raw Ethereum mainnet transaction (chain ID 1) and the V field is 28 — can you classify what type of signature that is and what chain ID it implies?”
Agent wallet signing sanity check
“My agent just signed a transaction and got back V=2710 — can you run the EVM signature V classify check against chain ID 137 so I know if this is a valid EIP-155 encoding or something unexpected?”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/evm-signature-v-classifyWhen to prefer
Use this endpoint when an AI agent needs to programmatically determine the signing scheme of an EVM transaction's V parameter — particularly during transaction pre-flight checks, wallet debugging, or when building cross-chain transaction relayers. It is preferred over manual lookup when the agent must handle multiple chains or legacy vs EIP-155 signatures dynamically. Ideal for agents that process raw transactions and need to validate signature encoding before broadcasting.
Side effects
- Missing or invalid V integer returns a validation error
- Missing or invalid chain_id returns a validation error
- V value inconsistent with any known classification may return an unexpected or unrecognized classification
- Network or service unavailability returns a 5xx error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| v | integer | V supplied to EVM Signature V Classify; used only for this bounded calculation and processed in memory without retention. |
| chain_id | integer | Chain Id supplied to EVM Signature V Classify; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"v": 27,
"classification": "legacy",
"expected_chain_id": 8453
},
"schema": "delx/util-evm-signature-v-classify/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "7717f04f6d982d96f99fcfa69caef99e8c3090309ae581ae53da0c8612700635",
"external_calls": 0
},
"operation": "evm_preflight:evm_signature_v_classify"
}
}Tags
x402
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