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auth-kit

@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.