| title | Migrate to Etherscan API V2: Multichain Unified Endpoint |
|---|---|
| sidebarTitle | V2 Migration |
| description | Upgrade from deprecated Etherscan API V1 or chain-specific explorer APIs (PolygonScan, BscScan) to the unified Etherscan API V2 in four steps. |
Etherscan API V2 introduces a unified multichain experience across 60+ supported networks under a single account and API key. If you're still using V1 endpoints or chain-specific explorer APIs like PolygonScan or BscScan, follow this guide to migrate your integration.
**V1 endpoints have been deprecated as of August 15, 2025.** If you're still using the legacy V1 base URL, your requests will return the following error:{
"status": "0",
"message": "NOTOK",
"result": "You are using a deprecated V1 endpoint, switch to Etherscan API V2."
}All existing endpoints remain fully compatible once you update to the V2 format.
[Contract verification](/contract-verification/verify-with-foundry) via Hardhat, Remix, and Foundry also supports a single Etherscan API key across all chains. [Sign up](https://etherscan.io/register) for an Etherscan account if you don't already have one. This applies whether you're migrating from V1 or from another explorer such as BaseScan, BscScan, or PolygonScan. Log in and go to your [API Dashboard](https://etherscan.io/apidashboard) to create a new API key. This single key grants access to all [supported chains](/supported-chains) under API V2 — you no longer need separate keys per chain. Update your base URL from the legacy V1 path to the new V2 path, and add the `chainid` parameter to specify your target network (use `1` for Ethereum Mainnet).**Before (V1):**
```text
https://api.etherscan.io/api?module=account&action=balance&apikey=YourEtherscanApiKey
```
**After (V2):**
```text
https://api.etherscan.io/v2/api?chainid=1&module=account&action=balance&apikey=YourEtherscanApiKey
```
That's the only change required for existing Etherscan V1 integrations — all module/action pairs and parameters remain the same.
**Before (PolygonScan V1):**
```text
https://api.polygonscan.com/api?module=account&action=balance&apikey=YourPolygonscanApiKey
```
**After (V2):**
```text
https://api.etherscan.io/v2/api?chainid=137&module=account&action=balance&apikey=YourEtherscanApiKey
```
Use `chainid=137` for Polygon, `chainid=56` for BNB Smart Chain, `chainid=8453` for Base, and so on. See the full [supported chains](/supported-chains) reference for every available chain ID.