Gas feesGas feesReturns JSON with live gas fees for Ethereum and Base (base fee, slow, standard and fast EIP-1559 priority and max fees in gwei, transfer cost) and Solana priority fees, in one call.
Use when you need a gas price or fee estimate before a transaction on Ethereum, Base or Solana, or to compare gas fees across chains.
Do not use for gas units of a given transaction, gas history or chains beyond Ethereum, Base and Solana.
Price: 0.003 USDC per call (x402, eip155:8453). Typical response time: 1500 ms (p95).
POST https://x402-gateway.blackwoodstate8.workers.dev/v1/gas-fees. A request without payment gets 402 Payment Required with the
PAYMENT-REQUIRED header; any x402 client signs an EIP-3009 authorization and retries with
PAYMENT-SIGNATURE (or X-PAYMENT). Invalid input is answered with 400 and not charged.
curl -i -X POST https://x402-gateway.blackwoodstate8.workers.dev/v1/gas-fees -H 'content-type: application/json' -d '{}'
| Pay to | 0x1cB6AaC2eAbF9644a22f17B0E758061f8412a7E1 |
|---|---|
| Asset | 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 (USDC) |
| Amount | 3000 atomic units (0.003 USDC) |
| Authorization window | 60 s |
Streamable HTTP at https://x402-gateway.blackwoodstate8.workers.dev/mcp, tool blackwood_gas_fees. Payment goes in
_meta["x402/payment"]; without it the tool returns the payment requirements.
| Field | Type | Meaning |
|---|---|---|
chains (optional) | array | Chains to read (ethereum, base and solana when omitted), e.g. ["base", "ethereum"] |
Example:
{}
Real example:
{
"ethereum": {
"chainId": 1,
"blockNumber": 26216462,
"baseFeeGwei": 0.0413101,
"nextBaseFeeGwei": 0.0374734,
"gasPriceGwei": 0.0413101,
"priorityFeeGwei": {
"slow": 0.000024942,
"standard": 0.00134048,
"fast": 1
},
"maxFeeGwei": {
"slow": 0.0749717,
"standard": 0.0762873,
"fast": 1.07495
},
"transferCostEth": {
"slow": 7.87465e-7,
"standard": 8.15091e-7,
"fast": 0.0000217869
}
},
"base": {
"chainId": 8453,
"blockNumber": 52750593,
"baseFeeGwei": 0.005,
"nextBaseFeeGwei": 0.005,
"gasPriceGwei": 0.006,
"priorityFeeGwei": {
"slow": 0,
"standard": 0.001,
"fast": 0.005
},
"maxFeeGwei": {
"slow": 0.01,
"standard": 0.011,
"fast": 0.015
},
"transferCostEth": {
"slow": 1.05e-7,
"standard": 1.26e-7,
"fast": 2.1e-7
}
},
"solana": {
"slot": 458268792,
"baseFeeLamportsPerSignature": 5000,
"priorityFeeMicroLamportsPerCu": {
"min": 0,
"low": 0,
"medium": 2673,
"high": 50000,
"veryHigh": 2000000
}
},
"updatedAt": "2026-10-18T02:28:53.602Z",
"note": "Gas in gwei. EIP-1559 tiers are the median 10th, 50th and 90th percentile priority fees of the last 20 blocks; max fee = 2 x next base fee + priority fee; transfer cost is a 21,000-gas ETH transfer. Solana: priority fee levels in micro-lamports per compute unit, on top of 5,000 lamports per signature."
}
{
"type": "object",
"properties": {
"ethereum": {
"anyOf": [
{
"type": "object",
"properties": {
"chainId": {
"type": "number"
},
"blockNumber": {
"type": "number"
},
"baseFeeGwei": {
"type": "number"
},
"nextBaseFeeGwei": {
"type": "number"
},
"gasPriceGwei": {
"type": "number"
},
"priorityFeeGwei": {
"type": "object",
"properties": {
"slow": {
"type": "number"
},
"standard": {
"type": "number"
},
"fast": {
"type": "number"
}
},
"required": [
"slow",
"standard",
"fast"
],
"additionalProperties": false
},
"maxFeeGwei": {
"type": "object",
"properties": {
"slow": {
"type": "number"
},
"standard": {
"type": "number"
},
"fast": {
"type": "number"
}
},
"required": [
"slow",
"standard",
"fast"
],
"additionalProperties": false
},
"transferCostEth": {
"type": "object",
"properties": {
"slow": {
"type": "number"
},
"standard": {
"type": "number"
},
"fast": {
"type": "number"
}
},
"required": [
"slow",
"standard",
"fast"
],
"additionalProperties": false
}
},
"required": [
"chainId",
"blockNumber",
"baseFeeGwei",
"nextBaseFeeGwei",
"gasPriceGwei",
"priorityFeeGwei",
"maxFeeGwei",
"transferCostEth"
],
"additionalProperties": false
},
{
"type": "null"
}
]
},
"base": {
"anyOf": [
{
"type": "object",
"properties": {
"chainId": {
"type": "number"
},
"blockNumber": {
"type": "number"
},
"baseFeeGwei": {
"type": "number"
},
"nextBaseFeeGwei": {
"type": "number"
},
"gasPriceGwei": {
"type": "number"
},
"priorityFeeGwei": {
"type": "object",
"properties": {
"slow": {
"type": "number"
},
"standard": {
"type": "number"
},
"fast": {
"type": "number"
}
},
"required": [
"slow",
"standard",
"fast"
],
"additionalProperties": false
},
"maxFeeGwei": {
"type": "object",
"properties": {
"slow": {
"type": "number"
},
"standard": {
"type": "number"
},
"fast": {
"type": "number"
}
},
"required": [
"slow",
"standard",
"fast"
],
"additionalProperties": false
},
"transferCostEth": {
"type": "object",
"properties": {
"slow": {
"type": "number"
},
"standard": {
"type": "number"
},
"fast": {
"type": "number"
}
},
"required": [
"slow",
"standard",
"fast"
],
"additionalProperties": false
}
},
"required": [
"chainId",
"blockNumber",
"baseFeeGwei",
"nextBaseFeeGwei",
"gasPriceGwei",
"priorityFeeGwei",
"maxFeeGwei",
"transferCostEth"
],
"additionalProperties": false
},
{
"type": "null"
}
]
},
"solana": {
"anyOf": [
{
"type": "object",
"properties": {
"slot": {
"type": "number"
},
"baseFeeLamportsPerSignature": {
"type": "number"
},
"priorityFeeMicroLamportsPerCu": {
"type": "object",
"properties": {
"min": {
"type": "number"
},
"low": {
"type": "number"
},
"medium": {
"type": "number"
},
"high": {
"type": "number"
},
"veryHigh": {
"type": "number"
}
},
"required": [
"min",
"low",
"medium",
"high",
"veryHigh"
],
"additionalProperties": false
}
},
"required": [
"slot",
"baseFeeLamportsPerSignature",
"priorityFeeMicroLamportsPerCu"
],
"additionalProperties": false
},
{
"type": "null"
}
]
},
"updatedAt": {
"type": "string"
},
"note": {
"type": "string"
},
"next": {
"type": "object",
"properties": {
"service": {
"type": "string",
"description": "Service id of the suggested next paid call"
},
"tool": {
"type": "string",
"description": "MCP tool name of the same call"
},
"method": {
"type": "string",
"enum": [
"GET",
"POST"
]
},
"url": {
"type": "string",
"description": "Paid route of the next call"
},
"useWhen": {
"type": "string",
"description": "When the next call is the right one"
},
"sample": {
"type": "string",
"description": "Free fixed sample of the whole family"
}
},
"required": [
"service",
"tool",
"method",
"url",
"useWhen",
"sample"
],
"additionalProperties": false,
"description": "Suggested next paid call in the same family (call it in a loop when the task continues)"
}
},
"required": [
"ethereum",
"base",
"solana",
"updatedAt",
"note"
],
"additionalProperties": false
}Free schema and example: GET https://x402-gateway.blackwoodstate8.workers.dev/v1/gas-fees.
OpenAPI 3.1 · llms.txt · All services