@farcaster/auth-kit

A React library that makes it easy to add Sign In With Farcaster to your application.

Getting Started

Installation

Install AuthKit and its peer dependency viem.

npm install @farcaster/auth-kit viem

Note: AuthKit is a React library. If you're using another frontend framework, take a look at the @farcaster/auth-client library instead.

Import

Import styles and functions.

import "@farcaster/auth-kit/styles.css";
import { AuthKitProvider } from "@farcaster/auth-kit";

Add Provider

Wrap your application with AuthKitProvider.

const config = {
  // For a production app, replace this with an Optimism Mainnet
  // RPC URL from a provider like Alchemy or Infura.
  rpcUrl: "https://mainnet.optimism.io",
  domain: "example.com",
  siweUri: "https://example.com/login",
};

const App = () => {
  return <AuthKitProvider config={config}>{/* Your App */}</AuthKitProvider>;
};

Add the sign in button

Then, in your app, import and render the SignInButton component.

import { SignInButton } from "@farcaster/auth-kit";

export const SignIn = ({ nonce }: { nonce: string }) => {
  return <SignInButton nonce={nonce} />;
};

A Sign in with Farcaster button will be rendered. When the user clicks it they will be prompted to complete sign in using their Farcaster wallet application. Once they complete sign in a signed message will be returned to your callback.

Examples

You can find official examples here.

Troubleshooting

Projects using Create React App (CRA) may run into TypeScript version conflicts, as [email protected] expects a peer dependency of TypeScript version ^3.2.1 || ^4, while both viem and AuthKit require >=5.0.4.

To resolve this issue:

• Install the latest version of TypeScript: npm i typescript -D
• Add an override for react-scripts to your package.json file, to remove the version ceiling:

"overrides": {
  "react-scripts": {
    "typescript": ">3.2.1"
  }
}

Note: Always be careful with overrides and ensure they are compatible with the packages using them.

Components

AuthKitProvider

Wrap your application in an AuthKitProvider to use Farcaster Auth.

const config = {
  domain: "example.com",
  siweUri: "https://example.com/login",
  rpcUrl: "https://mainnet.optimism.io",
  relay: "https://relay.farcaster.xyz",
};

const App = () => {
  return <AuthKitProvider config={config}>{/* Your App */}</AuthKitProvider>;
};

Props

config options:

SignInButton

The main component. Renders a "Sign in With Farcaster" button that prompts the user to scan a QR code with their phone on web or redirects directly on a mobile device. You can use a callback prop or a hook to access the user's authentication status and profile information.

import { SignInButton } from "@farcaster/auth-kit";

export const SignIn = ({ nonce }: { nonce: string }) => {
  return (
    <SignInButton
      nonce={nonce}
      onSuccess={({ fid, username }) =>
        console.log(`Hello, ${username}! Your fid is ${fid}.`)
      }
    />
  );
};

Props

Hooks

useSignIn

Hook for signing in a user. Connects to the relay server, generates a QR code and sign in link to present to the user, and polls relay server for wallet signature.

import { QRCode, useSignIn } from "@farcaster/auth-kit";

function App() {
  const {
    signIn,
    url
    data: { username },
    onSuccess: ({ fid }) => console.log("Your fid:", fid);
  } = useSignIn();

  return (
    <div>
      <button onClick={signIn}>Sign In</button>
      {qrCodeUri && (
        <span>
          Scan this: <QRCode uri={url} />
        </span>
      )}
      {username && `Hello, ${username}!`}
    </div>
  );
}

Parameters

Returns

  {
    signIn: () => void;
    reconnect: () => void;
    isSuccess: boolean;
    isPolling: boolean;
    isError: boolean;
    error: AuthClientError;
    channelToken: string;
    url: string;
    qrCodeUri: string;
    data: {
        state: "pending" | "complete";
        nonce: string;
        message: string;
        signature: string;
        fid: number;
        username: string;
        bio: string;
        displayName: string;
        pfpUrl: string;
        custody: Hex;
        verifications: Hex[];
    },
    validSignature: boolean;
  };

useProfile

Hook for reading information about the authenticated user.

import { useProfile } from "@farcaster/auth-kit";

function App() {
  const {
    isAuthenticated,
    profile: { fid, pfpUrl, username, displayName, bio },
  } = useProfile();

  return (
    <div>
     { isAuthenticated ? <p>Hello, {username}! Your fid is {fid}.<p>  : <p>You're not signed in.</p>}
    </div>
  );
}

Returns

  {
    isAuthenticated: boolean;
    profile: {
        fid: number;
        username: string;
        bio: string;
        displayName: string;
        pfpUrl: string;
    },
  };

useSignInMessage

Hook for reading the SIWE message and signature used to authenticate the user.

import { useSignInMessage } from "@farcaster/auth-kit";

function App() {
  const { message, signature } = useSignInMessage();

  return (
    <div>
      <p>You signed: {message}</p>
      <p>Your signature: {signature}</p>
    </div>
  );
}

Returns

{
  message: string;
  signature: string;
}