V2 Migration

As of August 15th 2025, we've deprecated the legacy V1 endpoints in favor or the new Etherscan API V2, our latest multichain update.

To reiterate, all methods including balances, source code, remain accessible (and better if you're querying multiple chains 🌈) once you use the new V2 format.

A legacy V1 endpoint that needs to be migrated looks like these

https://api.etherscan.io/api
https://api.basescan.org/api
https://api.polygonscan.com/api
https://api.bscscan.com/api
https://api.apescan.io/api

You'd also know if you get a deprecation error message

{
   "status":"0",
   "message":"NOTOK",
   "result":"You are using a deprecated V1 endpoint, switch to Etherscan API V2."
}

A word about tooling that uses the APIs, such as Hardhat/Foundry/Remix have all migrated. If you're seeing this error, make sure to use an Etherscan API Key.

1. Create an Etherscan account

Sign up if you don't have an account of if you were using other explorers like BaseScan/BscScan/Polygonscan etc.

2. Create an Etherscan API Key

Under your Etherscan API dashboard, create a new key

3. Using Your Existing Calls

All V1 endpoints are backwards compatible, so if you had

https://api.etherscan.io/api?&action=balance&apikey=YourEtherscanApiKeyToken

You only need to add the /v2 and a chainid

https://api.etherscan.io/v2/api?chainid=1&action=balance&apikey=YourEtherscanApiKeyToken

4. Using Your Existing Calls From Other Explorers

All V1 endpoints from other explorers such as Basescan/BscScan/Polygonscan etc are backwards compatible, so if you had

https://api.polygonscan.com/api?&action=balance&apikey=YourPolygoncsanApiKeyToken

You only need to use an Etherscan /v2 path, include a chainid and use your Etherscan API Key.

https://api.etherscan.io/v2/api?chainid=1&action=balance&apikey=YourEtherscanApiKeyToken