> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hyperauth.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# GET /api/balance

> Returns the native ETH or ERC-20 USDC balance for any address on a supported chain, useful for displaying wallet balances inside HyperAuth-powered apps.

Returns the native ETH or USDC balance for an address on a given chain.

## Query parameters

| Parameter | Type     | Required | Description                            |
| --------- | -------- | -------- | -------------------------------------- |
| `account` | `string` | Yes      | 20-byte EVM address                    |
| `token`   | `string` | Yes      | `"ETH"` or `"USDC"` (case-insensitive) |
| `chainId` | `string` | Yes      | Integer chain ID                       |

## Supported chains

| Chain ID | Network      | USDC address                                 |
| -------- | ------------ | -------------------------------------------- |
| `84532`  | Base Sepolia | `0x036CbD53842c5426634e7929541eC2318f3dCF7e` |
| `8453`   | Base Mainnet | `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` |

## Response (200)

```json theme={null}
{
  "balance": "1000000",
  "decimals": 6,
  "symbol": "USDC",
  "formatted": "1.000000"
}
```

For ETH, `decimals` is `18` and `symbol` is `"ETH"`.

## Errors

| Code  | `error`                                               | Condition                   |
| ----- | ----------------------------------------------------- | --------------------------- |
| `400` | `"Missing query parameters: account, token, chainId"` | Parameter absent            |
| `400` | `"Unsupported token. Supported: ETH, USDC"`           | Unknown token               |
| `400` | `"Unsupported chainId"`                               | Chain not in supported list |
| `400` | `"USDC not available on this chain"`                  | USDC address not known      |
| `502` | `"rpc_error"`                                         | Upstream eth\_call failure  |