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Crossmint Auth is designed for staging and moving fast. For production applications, Crossmint strongly recommends connecting your own authentication provider for full control over user management. See the Bring Your Own Auth guide.
Crossmint Auth provides a way to retrieve and update user profile data, such as email, social login metadata, and more.
The user object contains the following information:
  • id: User’s unique identifier.
  • email: User’s email address.
  • phoneNumber: User’s phone number.
  • farcaster: User’s Farcaster account data.
  • twitter: User’s Twitter (X) account data.
Farcaster Account data contains:
  • fid: User’s Farcaster ID.
  • username: User’s Farcaster username.
  • bio: User’s Farcaster bio.
  • displayName: User’s Farcaster display name.
  • pfpUrl: User’s Farcaster profile image URL.
  • custody: User’s FID custody address.
  • verifications: List of the user’s verified addresses.
Twitter Account data contains:
  • id: User’s Twitter ID.
  • username: User’s Twitter username.

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Reading User Data

This API requires the users.read scope.
  • Server side: Requires a server-side API key.
  • Client side: Requires a client-side API key, and a logged in user.

​
Server-side

For server-side operations, use the @crossmint/server-sdk that provides a getUser function to fetch user information. 
import { createCrossmint, CrossmintAuth } from "@crossmint/server-sdk";

const crossmint = createCrossmint({ apiKey: "<YOUR_SERVER_API_KEY>" });
const crossmintAuth = CrossmintAuth.from(crossmint);

async function getUser(userId: string) {
    try {
        const user = await crossmintAuth.getUser(userId);
        console.log("User data:", user);
    } catch (error) {
        console.error("Error fetching user data:", error);
    }
}

​
Response Format

{
    "id": "123",
    "email": "test@test.com", // Optional (if user was created with email)
    "phoneNumber": "123456789", // Optional (if user was created with phone number)
    "farcaster": {
        "fid": "123",
        "username": "johndoe",
        "bio": "Hello, I'm John Doe",
        "displayName": "John Doe",
        "pfpUrl": "https://example.com/pfp.jpg",
        "custody": "0x1234567890123456789012345678901234567890",
        "verifications": ["0x1234567890123456789012345678901234567890"]
    },
    "twitter": {
        "id": "456",
        "username": "johndoe"
    }
}

​
Client-side

Use the useAuth react hook from @crossmint/client-sdk-react-ui to access the user object.
If you would like to use a different framework, contact support
React
import { useAuth } from "@crossmint/client-sdk-react-ui";

function User() {
    const { user } = useAuth();

    if (!user) {
        return <div>Loading user...</div>;
    }

    return (
        <div>
            <h1>User</h1>
            <p>User ID: {user.id}</p>
            <p>Email: {user.email}</p>
            <p>Phone Number: {user.phoneNumber}</p>
            <p>Farcaster FID: {user.farcaster?.fid}</p>
            <p>Farcaster Username: {user.farcaster?.username}</p>
            <p>Farcaster Bio: {user.farcaster?.bio}</p>
            <p>Farcaster Display Name: {user.farcaster?.displayName}</p>
            <p>Farcaster PFP URL: {user.farcaster?.pfpUrl}</p>
            <p>Farcaster Custody: {user.farcaster?.custody}</p>
            <p>Farcaster Verifications: {user.farcaster?.verifications}</p>
            <p>Twitter ID: {user.twitter?.id}</p>
            <p>Twitter Username: {user.twitter?.username}</p>
        </div>
    );
}