# viem (/integrations/viem)



butr owns wallet discovery and connection state. viem owns chain abstraction
and RPC. The bridge is one line: `getSigner()` on an EVM adapter returns the
raw EIP-1193 provider — exactly what viem's `custom()` transport wants.

## Wire the wallet client [#wire-the-wallet-client]

```tsx
import { createWalletClient, custom, type EIP1193Provider } from "viem";
import { sepolia } from "viem/chains";

useEffect(() => {
  let cancelled = false;
  void (async () => {
    const provider = (await wallet.connector.getSigner()) as EIP1193Provider;
    if (cancelled) {
      return;
    }
    setWalletClient(
      createWalletClient({
        account,
        chain: sepolia,
        transport: custom(provider),
      }),
    );
  })();
  return () => {
    cancelled = true;
  };
}, [account, wallet.connector]);
```

`account` is `wallet.account.walletAddress` cast to viem's `Address`.

## Read, sign, send [#read-sign-send]

Reads go through viem's own public client (its RPC, not the wallet's, so you
don't double-spend the wallet on `eth_getBalance`):

```ts
const publicClient = createPublicClient({ chain: sepolia, transport: http() });
const wei = await publicClient.getBalance({ address: account });
const eth = `${formatEther(wei)} ETH`;
```

Signing and sending go through the wallet client (the real wallet):

```ts
const sig = await walletClient.signMessage({ account, message: "Hello from butr + viem" });

const hash = await walletClient.sendTransaction({
  account,
  chain: sepolia,
  to: BURN_ADDRESS,
  value: parseEther("0"),
});
```

The split is the whole point: **butr handles discovery + connection; viem
handles chain reads, signing, and tx submission against the provider butr
exposes.**

<Callout type="info">
  **Source:** `apps/demo-with-viem/src/app.tsx` in the [butr
  repository](https://github.com/pedroapfilho/usebutr/tree/main/apps/demo-with-viem). Targets
  Sepolia. Run `pnpm dev --filter=demo-with-viem` → `http://localhost:5175`.
</Callout>