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

# CrossmintEvmWalletCheckoutPayer

> Flutter Final Class

**Final Class**

Bridges a `CrossmintEvmWallet` into the checkout payer contract.

```dart theme={null}
final class CrossmintEvmWalletCheckoutPayer implements CrossmintCheckoutPayer
```

This adapter is intentionally EVM-only. The embedded checkout sends raw
serialized EVM transactions, and the runtime wallet forwards those
through the wallet transaction APIs using the same raw-transaction shape as
the JS wallet SDK.

## Constructors

### CrossmintEvmWalletCheckoutPayer

```dart theme={null}
CrossmintEvmWalletCheckoutPayer({
  required CrossmintEvmWallet wallet,
  List<String>? supportedChains,
  String? initialChain,
})
```

Creates an EVM payer backed by `wallet`.

## Properties

### supportedChains

```dart theme={null}
final List<String> supportedChains
```

EVM chains the wallet can sign transactions on. Computed from the `supportedChains` argument (defaulting to `[wallet.chain]`) and normalized to drop duplicates and blanks.

### address

```dart theme={null}
String get address
```

EVM address of the backing `CrossmintEvmWallet`.

### walletProviderKey

```dart theme={null}
String? get walletProviderKey
```

Always `null` — this adapter wraps an SDK-owned `CrossmintEvmWallet` rather than a third-party wallet provider, so there is no provider key to report.

### initialChain

```dart theme={null}
String get initialChain
```

Chain currently selected for outgoing transactions. Starts at the `initialChain` constructor argument (defaulting to `wallet.chain`) and updates when the hosted checkout calls `switchChain`.

## Methods

### signAndSendTransaction

```dart theme={null}
Future<CrossmintCheckoutTransactionResult> signAndSendTransaction(
  String serializedTransaction,
)
```

Signs and broadcasts a raw serialized EVM transaction received from the hosted checkout via the backing `CrossmintEvmWallet`. Returns `CrossmintCheckoutTransactionSuccess` with the transaction id on success. Errors are caught and surfaced as `CrossmintCheckoutTransactionFailure` — this method never throws so the hosted checkout can render a user-facing message.

### switchChain

```dart theme={null}
Future<void> switchChain(String chain)
```

Switches the selected chain used for subsequent transactions. Throws `ArgumentError` when `chain` is not in `supportedChains`. Called by the hosted checkout when the user changes chain in the UI.

### signMessage

```dart theme={null}
Future<String> signMessage(String message)
```

Signs an arbitrary message with the backing EVM wallet's approval signer. Returns the hex-encoded signature.