Multi-chain Explorer API

Query Etherscan-compatible block explorer APIs for transaction history, contract source code, ABIs, and gas data.

Supported Explorers

Chain	Base URL	Env Var (optional override)
Ethereum	`https://api.etherscan.io/api`	`ETHERSCAN_API_KEY`
BSC	`https://api.bscscan.com/api`	`BSCSCAN_API_KEY` or same key
Polygon	`https://api.polygonscan.com/api`	`POLYGONSCAN_API_KEY`
Arbitrum	`https://api.arbiscan.io/api`	`ARBISCAN_API_KEY`
Optimism	`https://api-optimistic.etherscan.io/api`	`OPTIMISM_API_KEY`
Base	`https://api.basescan.org/api`	`BASESCAN_API_KEY`

All explorers accept the apikey parameter. Many share a single Etherscan key, but some chains require separate registration.

Rate limit: 5 calls/second per key.