> For the complete documentation index, see [llms.txt](https://docs.baas.sh/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.baas.sh/baas-sdk/authentication/external-wallet.md).

# External wallet

Pair BaaS with a wallet the user already has, such as MetaMask, Rainbow, or Coinbase Wallet. Their existing address becomes the BaaS account.

## Sign up

With external wallets, sign up happens automatically on the first sign-in. The wallet is the account, so the same `signInWithWallet()` call covers both first-time and returning users.

## Sign in

Pass an EIP-1193 provider such as `window.ethereum`, or a connector's provider from wagmi.

```ts
import type { EIP1193Provider } from '@baas/sdk';

// MetaMask / browser-injected wallet
const session = await baas.auth.signInWithWallet(window.ethereum as EIP1193Provider);

// Any wagmi connector also works
const provider = await connector.getProvider();
const session = await baas.auth.signInWithWallet(provider);
```

The user sees **two** wallet prompts: one to connect, one to sign the message. That's standard wallet UX.

## Next

* [Passkeys](/baas-sdk/authentication/passkeys.md) — sign in with the device's built-in authenticator.
* [Sessions](/baas-sdk/authentication/sessions.md) — read the session, listen for changes, and sign out.


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