@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 react-scripts@5.0.1 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

Prop	Type	Required	Description
config	AuthKitConfig	Yes	Configuration object. See options in the table below.

config options:

Parameter	Type	Required	Description	Default
domain	string	Yes	Domain of your application.	None
siweUri	string	Yes	A URI identifying your application.	None
relay	string	No	Farcaster Auth relay server URL	https://relay.farcaster.xyz
rpcUrl	string	No	Optimism RPC server URL	https://mainnet.optimism.io
version	string	No	Farcaster Auth version	v1

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

Prop	Type	Required	Description	Default
timeout	number	No	Relay server timeout in ms.	300000 (5 minutes)
interval	number	No	Relay server polling interval in ms.	1500 (1.5 seconds)
nonce	string	No	Random nonce to include in the Sign In With Farcaster message.	None
notBefore	string	No	Time when the SIWF message becomes valid. ISO 8601 datetime string.	None
expirationTime	string	No	Time when the SIWF message expires. ISO 8601 datetime string.	None
requestId	string	No	An optional system specific ID to include in the SIWF message.	None
onSuccess	(res: UseSignInData) => void	No	Callback invoked when sign in is complete and the user is authenticated.	None
onStatusResponse	(res: UseWatchStatusData) => void	No	Callback invoked when the component receives a status update from the relay server.	None
onError	(error: AuthClientError) => void	No	Error callback function.	None
debug	boolean	No	Render a debug panel displaying internal AuthKit state.	false

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

Parameter	Type	Required	Description	Default
timeout	number	No	Relay server timeout in ms.	300000 (5 minutes)
interval	number	No	Relay server polling interval in ms.	1500 (1.5 seconds)
nonce	string	No	Random nonce to include in the Sign In With Farcaster message.	None
notBefore	string	No	Time when the SIWF message becomes valid. ISO 8601 datetime string.	None
expirationTime	string	No	Time when the SIWF message expires. ISO 8601 datetime string.	None
requestId	string	No	An optional system specific ID to include in the SIWF message.	None
onSuccess	(res: UseSignInData) => void	No	Callback invoked when sign in is complete and the user is authenticated.	None
onStatusResponse	(res: UseWatchStatusData) => void	No	Callback invoked when the component receives a status update from the relay server.	None
onError	(error: AuthClientError) => void	No	Error callback function.	None

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;
  };

Parameter	Description
signIn	Call this function to connect to the relay and poll for a signature.
reconnect	Reconnect to the relay and try again. Use in the event of an error.
isSuccess	True when the relay server returns a valid signature.
isPolling	True when the relay state is "pending" and the app is polling the relay server for a response.
isError	True when an error has occurred.
error	AuthClientError instance.
channelToken	Farcaster Auth relay channel token.
url	Sign in With Farcaster URL to present to the user. Links to Warpcast in v1.
qrcodeUri	QR code image data URI encoding url.
data.state	Status of the sign in request, either "pending" or "complete"
data.nonce	Random nonce used in the SIWE message. If you do not provide a custom nonce, read this value.
data.message	The generated SIWE message.
data.signature	Hex signature produced by the user's Warpcast wallet.
data.fid	User's Farcaster ID.
data.username	User's Farcaster username.
data.bio	User's Farcaster bio.
data.displayName	User's Farcaster display name.
data.pfpUrl	User's Farcaster profile picture URL.
data.custody	User's Farcaster ID custody address.
data.verifications	User's verified addresses.
validSignature	True when the signature returned by the relay server is valid.

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;
    },
  };

Parameter	Description
isAuthenticated	True if the user is authenticated.
profile.fid	User's Farcaster ID.
profile.username	User's Farcaster username.
profile.bio	User's Farcaster bio.
profile.displayName	User's Farcaster display name.
profile.pfpUrl	User's Farcaster profile picture URL.
profile.custody	User's Farcaster ID custody address.
profile.verifications	User's verified addresses.

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;
}

Parameter	Description
message	SIWE message signed by the user.
signature	Signature produced by the user's Warpcast wallet.