Using a wallet from another app

Once a user has authorized access to their account on other apps, via the cross-app ecosystem, you can use the wallets of that account to do things like sign messages and send transactions.

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 linked_accounts array of their user object. You can find this account like so:

const {user} = usePrivy();
const crossAppAccount = user.linked_accounts.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.
embedded_wallets	{address: string}[]	An array of the user's embedded wallet(s) from the provider app for the cross-app account.
smart_wallets	{address: string}[]	An array of the user's smart 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 embedded_wallets field of the crossAppAccount:

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

TIP

Cross-app operations on Smart Wallets work exactly the same! Just use the right wallet address and all hooks will work as usual.

const smartWalletAddress = crossAppAccount.smart_wallets[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 linked_accounts array. If your app permits users to link cross-app accounts from multiple provider apps, you should also filter the linked_accounts by the provider_app_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.linked_accounts.find(
  (account) => account.type === 'cross_app' && account.provider_app_id === providerAppId,
);

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

const address = crossAppAccount.embedded_wallets[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 embedded_wallets 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 hooks: useSignMessageWithCrossApp, useSignTypedDataWithCrossApp and useSendTransactionWithCrossApp:

These methods all require an additional address property, and an optional redirectUri, of the following types:

Parameter	Type	Description
address	string	The address for the cross-app embedded wallet that you'd like to request a signature/transaction from.
redirectUri	string	(Optional) A URL path that the provider will automatically redirect to after successful authentication. This defaults to a link back to your app root, eg. '/', if not provided.

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 `useSignMessageWithCrossApp``, pass the following parameters:

Parameter	Type	Description
message	string	The message the user must sign as a string.
address	string	The address for the cross-app embedded wallet that you'd like to request a signature/transaction from.
redirectUri	string	(Optional) A URL path that the provider will automatically redirect to after successful authentication. This defaults to a link back to your app root, eg. '/', if not provided.

signTypedData

To the signTypedData method returned by `useSignTypedDataWithCrossApp``, pass the following parameters:

Parameter	Type	Description
typedData	TypedDataDefinition	A JSON object that conforms to the EIP-712 TypedData JSON schema.
address	string	The address for the cross-app embedded wallet that you'd like to request a signature/transaction from.
redirectUri	string (optional)	A URL path that the provider will automatically redirect to after successful authentication. This defaults to a link back to your app root, eg. '/', if not provided.

sendTransaction

To the sendTransaction method returned by `useSendTransactionWithCrossApp``, pass the following parameters:

Parameter	Type	Description
requestData	UnsignedTransactionRequest	The transaction request to be sent.
address	string	The address for the cross-app embedded wallet that you'd like to request a signature/transaction from.
redirectUri	string (optional)	A URL path that the provider will automatically redirect to after successful authentication. This defaults to a link back to your app root, eg. '/', if not provided.

Example signature request

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

import {usePrivy, useSignMessageWithCrossApp} from '@privy-io/expo';

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

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