Register an Operational Signer for your Wallet

Previous versions of these guides used the term delegated signer. We have moved to operational signer as the standard terminology. The next breaking API / SDK version will adopt this naming convention in method signatures and types. Until then, the code snippets below still reference addDelegatedSigner and delegatedSigners.

Register an operational signer on an existing wallet for day-to-day operations. This signer can be set up with the wallet owner — for example, a device key for user wallets or a server key for company wallets. For an overview of available signer types, see Wallet Signers.

Prerequisites

Ensure you have a wallet created.
API Key: Ensure you have an API key with the scopes: wallets:signatures.create and wallets:transactions.create.

Adding an operational signer

React
Node.js
React Native
REST

import { useWallet } from '@crossmint/client-sdk-react-ui';

const { wallet } = useWallet();

const externalSigner = {
    type: "external-wallet",
    address: "0x1234567890123456789012345678901234567890"
}

await wallet.addDelegatedSigner({
    signer: externalSigner,
});

See the React SDK reference for more details.

import { CrossmintWallets, createCrossmint } from "@crossmint/wallets-sdk";

const crossmint = createCrossmint({
    apiKey: "<your-server-api-key>",
});

const crossmintWallets = CrossmintWallets.from(crossmint);

const wallet = await crossmintWallets.getWallet(
    "email:user@example.com:evm",
    { chain: "base-sepolia", signer: { type: "email" } }
);

const externalSigner = {
    type: "external-wallet",
    address: "0x1234567890123456789012345678901234567890"
}

await wallet.addDelegatedSigner({
    signer: externalSigner,
});

Parameters

signer

string | object

required

The locator of the signer to add.

import { useWallet } from '@crossmint/client-sdk-react-native-ui';

const { wallet } = useWallet();

const externalSigner = {
    type: "external-wallet",
    address: "0x1234567890123456789012345678901234567890"
}

await wallet.addDelegatedSigner({
    signer: externalSigner,
});

See the React Native SDK reference for more details.

Operational signers must be approved by the wallet’s recovery signer (called adminSigner in the current API). The SDK handles this automatically, but with the REST API you must approve the transaction (if using Solana, Stellar) or signature (if using EVM) to complete it.

Create the operational signer

Call the create delegated signer endpoint.

curl --request POST \
    --url https://staging.crossmint.com/api/2025-06-09/wallets/email:user@example.com:evm/signers \
    --header 'Content-Type: application/json' \
    --header 'X-API-KEY: <x-api-key>' \
    --data '{
        "chain": "base",
        "signer": "external-wallet:0x1234567890123456789012345678901234567890"
    }'

See the API reference for more details.

Sign the approval returned in the response

If you are using an api-key as the recovery signer (admin signer) you can skip the following steps.

Sign the approval message field returned in the response inside transaction.approvals (for EVM) or signature.approvals (for Solana and Stellar) using the recovery signer (admin signer).

Approve the transaction or signature to register the operational signer

EVM
Solana and Stellar

Call the approve signature endpoint using the signature from the previous step and the signature id returned in the call from Step 1.

curl --request POST \
    --url https://staging.crossmint.com/api/2025-06-09/wallets/email:user@example.com:evm/signatures/b984491a-5785-43c0-8811-45d46fe6e520/approvals \
    --header 'Content-Type: application/json' \
    --header 'X-API-KEY: <x-api-key>' \
    --data '{
        "approvals": [{
            "signer": "email:user@example.com",
            "signature": "0x1234567890abcdef..."
        }]
    }'

See the API reference for more details.

Call the approve transaction endpoint using the signature from the previous step and the transaction id returned in the call from Step 1.

curl --request POST \
    --url https://staging.crossmint.com/api/2025-06-09/wallets/email:user@example.com:solana/transactions/b984491a-5785-43c0-8811-45d46fe6e520/approvals \
    --header 'Content-Type: application/json' \
    --header 'X-API-KEY: <x-api-key>' \
    --data '{
        "approvals": [{
            "signer": "email:user@example.com",
            "signature": "5qY6wXw6zTn7..."
        }]
    }'

See the API reference for more details.

Listing all operational signers

React
Node.js
React Native
REST

import { useWallet } from '@crossmint/client-sdk-react-ui';

const { wallet } = useWallet();

const signers = await wallet.delegatedSigners();

See the React SDK reference for more details.

import { CrossmintWallets, createCrossmint } from "@crossmint/wallets-sdk";

const crossmint = createCrossmint({
    apiKey: "<your-server-api-key>",
});

const crossmintWallets = CrossmintWallets.from(crossmint);

const wallet = await crossmintWallets.getWallet(
    "email:user@example.com:evm",
    { chain: "base-sepolia", signer: { type: "email" } }
);

const signers = await wallet.delegatedSigners();

Returns

signers

DelegatedSigner[]

The operational signers.

Show properties

signer

string

The locator of the signer.

React Native

import { useWallet } from '@crossmint/client-sdk-react-native-ui';

const { wallet } = useWallet();

const signers = await wallet.delegatedSigners();

See the React Native SDK reference for more details.

curl --request GET \
    --url https://staging.crossmint.com/api/2025-06-09/wallets/email:user@example.com:evm \
    --header 'X-API-KEY: <x-api-key>'

See the API reference for more details.

Introduction

Quickstarts ⚡️

Concepts

Guides

API Reference

Registering a Signer

Prerequisites

Adding an operational signer

Parameters

Listing all operational signers

Returns

Introduction

Quickstarts ⚡️

Concepts

Guides

API Reference

​Prerequisites

​Adding an operational signer

​Parameters

​Listing all operational signers

​Returns

Prerequisites

Adding an operational signer

Parameters

Listing all operational signers

Returns