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App Client

If you're building a connected app and want users to sign in with Farcaster, use an AppClient.

You can use an AppClient to create a Farcaster Auth relay channel, generate a deep link to request a signature from the user's Farcaster wallet app, and verify the returned signature.

import { createAppClient, viemConnector } from '@farcaster/auth-client';

const appClient = createAppClient({
  relay: '',
  ethereum: viemConnector(),



An Ethereum connector, used to query the Farcaster contracts and verify smart contract wallet signatures. @farcaster/auth-client currently provides only the viem connector type.

To use a custom RPC, pass an RPC URL to the viem connector.

relaystringRelay server URL. Defaults to the public relay at https://relay.farcaster.xyzNo
versionstringFarcaster Auth version. Defaults to "v1"No