Pre-broadcast gas check: base fee + p50/p90 priority fee in gwei from eth_feeHistory, plus USD cost per common tx type (native transfer, ERC-20 transfer, swap) at live ETH/USD. Size gas budgets or postpone txs under congestion. Never returns null costs — degraded upstreams are a free 502, not a paid empty answer. Chains: ethereum, base, arbitrum, optimism.
| Network | Scheme | Amount | Pay To |
|---|---|---|---|
| Base | exact | $0.001000 USDC | 0x8eeF...b601 |