Integrating a wallet from another app

Privy allows you to easily integrate embedded wallets from other apps, to verify ownership of users' wallet addresses or even request signatures and transactions from.

This reduces friction around having users transact onchain in your app, as users can easily pull in their assets and identity from other apps where they may already have embedded wallets.

Within this setup, your app is known as the requester app.

Finding available providers

To integrate embedded wallets from another app, first visit the Privy Dashboard and navigate to the Ecosystem page for your app. From there, open the Integrations tab to see a list of provider app IDs that consent to sharing their wallets with other apps.

For any providers you'd like to integrate, note down the provider's Privy app ID, as you will use this value in the interfaces outlined below.

TIP

Some providers may only consent to sharing their users' wallets in read-only mode, in which case your app can verify that the user owns a particular address, but cannot request signatures or transactions from it.

Linking a wallet from a provider

To prompt users to link their embedded wallet from a provider app, use the linkCrossAppAccount method from the useCrossAppAccounts hook:

const {linkCrossAppAccount} = useCrossAppAccounts();

As a parameter to this method, pass an object containing the following fields:

Parameter	Type	Description
appId	string	Required. The Privy app ID of the provider app from which you'd like a user to link their account. You can find a list of Privy app IDs for provider apps in the Cross-app ecosystem page of the Privy Dashboard.

When linkCrossAppAccount is invoked, the user will be redirected to a page hosted on the domain of the provider app you specified to authorize access to your own app.

If the user successfully authorizes access, the user will be redirected back to your app, and an account of type: 'cross_app' will be added to the linkedAccounts array of their user object.

linkCrossAppAccount will throw an error if:

• The user does not authorize access to your app or exits the flow prematurely.
• The provider app you request has not opted-in to share their wallets.
• The user is not authenticated and thus cannot link an account from the provider app to an existing account within your requester's app.

TIP

If the user is already logged in on the domain of the source appId you specify in linkCrossAppAccount, they will not have to login again and will only have to consent to sharing access to that account in your app.

As an example, you might set up a button to link a cross-app wallet like so:

import {usePrivy} from '@privy-io/react-auth';

function Button() {
  const {ready, authenticated} = usePrivy();
  const {linkCrossAppAccount} = useCrossAppAccounts();

  return (
    <button
      onClick={() => linkCrossAppAccount({appId: 'insert-provider-app-id'})}
      disabled={!ready || !authenticated}
    >
      Link your [insert-provider-app-name] account
    </button>
  );
}

Getting linked provider wallets

Once a user has successfully linked their account from a provider app, an account of type: 'cross_app' will be added to the linkedAccounts array of their user object. You can find this account like so:

const {user} = usePrivy();
const crossAppAccount = user.linkedAccounts.find((account) => account.type === 'cross_app');

This crossAppAccount is an object with the following properties:

Field	Type	Value
type	'cross_app'	Indicates that the linked account is a cross-app account.
embeddedWallets	{address: string}[]	An array of the user's embedded wallet(s) from the provider app for the cross-app account.
providerApp	ProviderAppMetadata	Metadata about the provider app for the cross-app account.
firstVerifiedAt	Date	Datetime when the cross-app account was first linked to the user.
latestVerifiedAt	Date	Datetime for when the user last logged in/linked the cross-app account.

To get the user's embedded wallet address from this account, simply inspect the embeddedWallets field of the crossAppAccount:

const embeddedWalletAddress = crossAppAccount.embeddedWallets[0].address;

To get metadata about the provider app for the wallet, such as its Privy app ID, name, and logo, inspect the providerApp field of crossAppAccount:

const providerApp = crossAppAccount.providerApp;

This providerApp metadata is an object with the following properties:

Field	Type	Value
id	string	Privy app ID of the source app.
name	string?	Name of the source app.
logoUrl	string?	Logo of the source app.

Using wallets from a provider

Once a user has successfully linked a cross-app account, the user may use their embedded wallet from the provider app within your app per the interfaces below.

Getting the wallet address

To find a user's cross-app embedded wallet, first find the account of type: 'cross_app' from their linkedAccounts array. If your app permits users to link cross-app accounts from multiple provider apps, you should also filter the linkedAccounts by the providerApp.id on the cross-app account.

// Replace `providerAppId` with the Privy app ID of your desired provider app
const providerAppId = 'insert-provider-app-id';
const crossAppAccount = user.linkedAccounts.find(
  (account) => account.type === 'cross_app' && account.providerApp.id === providerAppId,
);

Next, from the crossAppAccount, inspect the embeddedWallets array to get the user's embedded wallet address(es) from the source app.

const address = crossAppAccount.embeddedWallets[0].address;

INFO

Most users only have one embedded wallet per app. Certain apps, however, leverage multiple embedded wallets (e.g. HD wallets) per user to support certain use cases. In kind, the embeddedWallets field is designed as an array, but generally will be a singleton containing one entry.

Requesting signatures and transaction

INFO

When you request a signature or transaction from a user's embedded wallet from another app, Privy requires the user to explicitly confirm the signature or transaction. This is accomplished by opening a popup to the provider app's domain, where the user confirms the action in an isolated environment.

To request signatures and transactions from a user's embedded wallet from a provider app, use the signMessage, signTypedData, and sendTransaction methods returned by Privy's useCrossAppAccounts hook:

import {useCrossAppAccounts} from '@privy-io/react-auth';

const {signMessage, signTypedData, sendTransaction} = useCrossAppAccounts();

These methods are similar to the signMessage, signTypedData, and sendTransaction methods returned by usePrivy except they all require an additional CrossAppWalletOptions object of the following type:

Parameter	Type	Description
address	string	Required. The address for the cross-app embedded wallet that you'd like to request a signature/transaction from.

If the address you specify in this CrossAppWalletOptions object is not a valid embedded wallet that has been linked to the current user from a provider app, these wallet methods will error.

Continue below for the specific parameters required by each method.

signMessage

To the signMessage method returned by useCrossAppAccounts, pass the following parameters:

Parameter	Type	Description
message	string	Required. The message the user must sign as a string.
options	CrossAppWalletOptions	Required. Options for the cross-app embedded wallet, which must include the requested wallet's address

signTypedData

Parameter	Type	Description
typedData	SignedTypedDataParams	Required. A JSON object that conforms to the EIP-712 TypedData JSON schema.
options	CrossAppWalletOptions	Required. Options for the cross-app embedded wallet, which must include the requested wallet's address

sendTransaction

Parameter	Type	Description
requestData	UnsignedTransactionRequest	Required. The transaction request to be sent.
options	CrossAppWalletOptions	Required. Options for the cross-app embedded wallet, which must include the requested wallet's address

Example signature request

As an example, you might request a signature from a user's cross-app wallet like so:

import {usePrivy, useCrossAppAccounts} from '@privy-io/react-auth';

function Button() {
  const {user} = usePrivy();
  const {signMessage} = useCrossAppAccounts();
  const crossAppAccount = user.linkedAccounts.find((account) => account.type === 'cross_app');
  const address = crossAppAccount.embeddedWallets[0].address;

  return (
    <button onClick={() => signMessage('Hello world', {address: address})} disabled={!address}>
      Sign a message with your cross-app wallet
    </button>
  );
}