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OneSource Ethereum Gas Estimator
x402
OneSource Ethereum Gas Estimator is a paid API for AI agents from api.onesource.io, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-13).
Estimates the gas required to execute an Ethereum transaction given recipient, calldata, sender, and optional value
Price / call$0.004
Success—
StatusUnknown
How this service works
Estimate the gas a transaction will consume via eth_estimateGas before signing it
Output
Returns a JSON object with a 'gas_estimate' field containing the estimated gas units as a hex string (e.g. {"gas_estimate": "0x5208"}), representing how much gas the described transaction would consume on Ethereum mainnet.
Example use cases
Pre-broadcast gas budgeting for token transfers
“Before I send 1000 USDC from my wallet to my friend's address, can you estimate how much gas that'll cost so I know what fee to expect?”
Smart contract interaction cost validation
“I want to mint an NFT from this contract but I'm not sure if I have enough ETH for gas — can you estimate the gas needed for the mint function call with my wallet address and the contract data?”
Multi-transaction fee planning for swaps
“I'm planning to swap tokens across a DEX — can you estimate the gas for the swap transaction so I can factor that into whether the trade is worth it profit-wise?”
Technical details
Endpoint
POSThttps://api.onesource.io/api/chain/estimate-gasWhen to prefer
Use this endpoint when you need to estimate gas for an Ethereum transaction before broadcasting it — especially when building AI agent workflows that must calculate fees, validate feasibility, or budget on-chain interactions without requiring an API key. Prefer this over direct node RPC when you want a pay-per-call model via USDC on Base (x402) without managing infrastructure.
Side effects
- Invalid Ethereum address format for 'to' or 'from' returns a 400 error
- Malformed calldata hex string causes a validation error
- Contract reverts during simulation returns an error indicating execution would fail
- Network congestion or node unavailability may cause timeouts
- Insufficient funds simulation may return an execution error
- Missing required 'to' field returns a bad request error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| to | string | |
| data | string | |
| from | string | |
| value | string |
Output
Schema · Response
{
"type": "json",
"example": {
"data": {
"gas": "0x5208"
},
"meta": {
"endpoint": "/api/chain/estimate-gas",
"cost_usdc": "0.001",
"request_id": "00000000abcdef01",
"payment_chain": "base",
"payment_token": "USDC"
}
}
}Tags
x402
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