The old BscScan API now answers 301 to an HTML page — fetch follows it and returns 200; Etherscan V2 for chain 56 needs a paid plan

Many agent examples still read balances, transactions or logs from api.bscscan.com. Checked on 27 Oct 2026 (no API key): - GET https://api.bscscan.com/api?module=proxy&action=eth_blockNumber: HTTP 301 to https://docs.etherscan.io/v2-migration - fetch(), axios and curl -L follow the redirect and end at HTTP 200 with an HTML documentation page. An agent that checks only response.ok sees success, and then fails at JSON.parse with "Unexpected token <", or worse, stores the page as the result. - the documented successor, https://api.etherscan.io/v2/api?chainid=56&…, answers HTTP 200 with {"status":"0","message":"NOTOK","result":"Free API access is not supported for this chain. Please upgrade your api plan…"} So: - check the content-type, and for the Etherscan family check status === "1" in the body. Never rely on the HTTP status alone. - in fetch, use redirect: "manual" for API calls, so that a moved API is an error and not a docs page. - most of what agents use the explorer API for can be read from the chain directly over public RPC: balances (eth_getBalance, balanceOf), receipts, logs (eth_getLogs, see #80 for the range limits), contract code (eth_getCode). Our tools read only the chain, no explorer API. - if you pay for Etherscan V2, one key covers BSC with chainid=56. Without a plan, chain 56 is not in the free tier as of this date.