Etherscan API V2
The canonical Ethereum + multichain explorer API: verified contract ABIs/source, tx lists, token transfers and balances from one free key.
Etherscan's V2 API unifies what used to be per-chain explorers (Etherscan, BscScan, PolygonScan, Arbiscan, etc.) under a single base URL and a single API key, selected per request with a chainid parameter spanning 60+ chains. It is the standard source for EVM account/contract data that raw JSON-RPC does not give you cheaply: normal and internal transaction lists, ERC-20/721/1155 token transfers, token balances, gas oracle, and crucially verified contract source code and ABIs. A free API key is still available and remains the easiest way to fetch a contract's ABI for decoding or interaction in a Claude Skill. Verified live June 2026.
Free tier
Free tier with a free API key (5 calls/sec, 100,000 calls/day). Paid plans (historically from ~$199/mo, plus a discounted Lite plan) raise limits and restore full chain coverage.Rate limits
Free tier: 5 requests/second and 100,000 requests/day, shared across all chains for one key. As of late 2025 the free tier covers ~90% of supported chains; verified-contract (source/ABI) endpoints remain free on every supported network.Auth
API keyBase URL
https://api.etherscan.io/v2/apiWhat you'd build with it
- Fetch a verified contract's ABI to decode events or call methods
- List an address's transactions and ERC-20 transfers
- Read token balances and total supply for tokens
- Query EVM chains (Polygon/Arbitrum/BSC) through one key via chainid
Key endpoints
- GET
?chainid=1&module=account&action=balanceNative ETH (or chain) balance for an address - GET
?chainid=1&module=account&action=txlistNormal transaction list for an address - GET
?chainid=1&module=account&action=tokentxERC-20 token transfer events for an address - GET
?chainid=1&module=contract&action=getabiVerified contract ABI (free on all chains) - GET
?chainid=1&module=contract&action=getsourcecodeVerified contract source code (free on all chains) - GET
?chainid=1&module=gastracker&action=gasoracleCurrent gas price oracle (safe/propose/fast)
Members get the runnable recipe
Sign in free to copy the example request, see a sample response, and read the gotchas.