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Delx EVM Legacy Fee Check
x402
Delx EVM Legacy Fee Check 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).
Validates whether a legacy (Type 0) EVM transaction's computed gas fee falls within a specified maximum budget ceiling.
Price / call$0.001
Success—
StatusUnknown
How this service works
EVM Legacy Fee Check: EVM Legacy Fee Check checks gasPrice and gasLimit values for a legacy transaction budget from bounded caller-supplied values without an external provider. Call EVM Legacy Fee Check 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 Legacy Fee Check as versioned deterministic JSON. Price: $0.001 U…
Output
Returns a JSON object indicating whether the computed fee (gas_limit × gas_price_wei) is within the specified maximum_fee_wei ceiling. Includes a boolean `within_budget` field, the computed `fee_ceiling_wei` value, a pass/fail `status`, and an evidence block confirming no data was retained and no external calls were made.
Example use cases
Pre-send gas budget guard for ETH transfer
“I'm about to send a legacy Ethereum transfer with a gas limit of 21000 and a gas price of 50 gwei (50000000000 wei). Can you check whether that fee is under my ceiling of 2000000000000000 wei before I broadcast it?”
DeFi swap preflight fee validation
“I want to make sure my DeFi swap won't bust my gas budget — gas limit is 200000, gas price is 15000000000 wei, and I can't spend more than 5000000000000000 wei in fees. Run a preflight check.”
Agent-automated batch transaction gating
“For each of these pending transactions, check if the legacy gas fee is within budget before queuing them — start with gas limit 150000, gas price 20000000000 wei, and a maximum fee of 3500000000000000 wei.”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/evm-legacy-fee-checkWhen to prefer
Use this endpoint when you need a fast, stateless, in-memory preflight check for legacy (Type 0) EVM transactions before broadcasting — particularly in agent pipelines where you want to gate transaction submission on a fee ceiling without making any external blockchain calls. Prefer this over on-chain simulation when you only need arithmetic validation of gas_limit × gas_price_wei against a budget, and you want a verifiable evidence trail (input hash, zero retention, zero external calls).
Side effects
- Missing required fields (gas_limit, gas_price_wei, or maximum_fee_wei) returns a validation error
- Non-numeric or malformed wei strings cause parse errors
- Gas price or maximum fee strings exceeding 8192 characters are rejected
- Integer overflow for extremely large gas values may produce unexpected results
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| gas_limit | integer | Gas Limit supplied to EVM Legacy Fee Check; used only for this bounded calculation and processed in memory without retention. |
| gas_price_wei | string | Gas Price Wei supplied to EVM Legacy Fee Check; used only for this bounded calculation and processed in memory without retention. |
| maximum_fee_wei | string | Maximum Fee Wei supplied to EVM Legacy Fee Check; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"within_budget": true,
"fee_ceiling_wei": "21000000000000"
},
"schema": "delx/util-evm-legacy-fee-check/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "3f479705a06db86ca332b2883b0bc646d76b8b39f7fea2aa864a00ee6e549ded",
"external_calls": 0
},
"operation": "evm_preflight:evm_legacy_fee_check"
}
}Tags
x402
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