EVM gas price API: current gas fees for Ethereum, Base, and Polygon — node-reported gas price plus EIP-1559 estimates from the last 5 blocks: next base fee and 25th/50th/75th-percentile priority fees, in gwei. Read directly from public JSON-RPC nodes with automatic fallbacks. Use for transaction cost estimation, fee optimization, and timing on-chain actions. Cached up to 15 seconds.