Create Signature

curl --request POST \
  --url https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <x-api-key>' \
  --data '
{
  "params": {
    "chain": "ethereum",
    "message": "Hello, world!",
    "signer": "external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E"
  },
  "type": "message"
}
'

import requests

url = "https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures"

payload = {
    "params": {
        "chain": "ethereum",
        "message": "Hello, world!",
        "signer": "external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E"
    },
    "type": "message"
}
headers = {
    "X-API-KEY": "<x-api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'X-API-KEY': '<x-api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    params: {
      chain: 'ethereum',
      message: 'Hello, world!',
      signer: 'external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E'
    },
    type: 'message'
  })
};

fetch('https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'params' => [
        'chain' => 'ethereum',
        'message' => 'Hello, world!',
        'signer' => 'external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E'
    ],
    'type' => 'message'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "X-API-KEY: <x-api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures"

	payload := strings.NewReader("{\n  \"params\": {\n    \"chain\": \"ethereum\",\n    \"message\": \"Hello, world!\",\n    \"signer\": \"external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E\"\n  },\n  \"type\": \"message\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("X-API-KEY", "<x-api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures")
  .header("X-API-KEY", "<x-api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"params\": {\n    \"chain\": \"ethereum\",\n    \"message\": \"Hello, world!\",\n    \"signer\": \"external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E\"\n  },\n  \"type\": \"message\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-API-KEY"] = '<x-api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"params\": {\n    \"chain\": \"ethereum\",\n    \"message\": \"Hello, world!\",\n    \"signer\": \"external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E\"\n  },\n  \"type\": \"message\"\n}"

response = http.request(request)
puts response.read_body

{
  "approvals": {
    "pending": [
      {
        "quorumApprovals": {
          "pending": [
            {
              "message": "<string>",
              "signer": {
                "address": "<string>",
                "locator": "<string>",
                "type": "api-key"
              }
            }
          ],
          "remaining": 123,
          "submitted": [
            {
              "message": "<string>",
              "signature": "<string>",
              "signer": {
                "address": "<string>",
                "locator": "<string>",
                "type": "api-key"
              },
              "submittedAt": 123
            }
          ],
          "threshold": 123
        },
        "signer": {
          "locator": "<string>",
          "type": "quorum"
        }
      }
    ],
    "required": 123,
    "submitted": [
      {
        "quorumApprovals": {
          "pending": [
            {
              "message": "<string>",
              "signer": {
                "address": "<string>",
                "locator": "<string>",
                "type": "api-key"
              }
            }
          ],
          "remaining": 123,
          "submitted": [
            {
              "message": "<string>",
              "signature": "<string>",
              "signer": {
                "address": "<string>",
                "locator": "<string>",
                "type": "api-key"
              },
              "submittedAt": 123
            }
          ],
          "threshold": 123
        },
        "signer": {
          "locator": "<string>",
          "type": "quorum"
        }
      }
    ]
  },
  "chainType": "aptos",
  "createdAt": 123,
  "id": "<string>",
  "params": {
    "authorizationEntries": "<string>",
    "signer": {
      "address": "<string>",
      "locator": "<string>",
      "type": "api-key"
    }
  },
  "status": "awaiting-approval",
  "type": "auth-entries",
  "walletType": "mpc",
  "completedAt": 123,
  "error": "<unknown>",
  "outputSignature": "<string>"
}

{
  "error": true,
  "message": "<error message>",
  "code": "DEVICE_SIGNER_NOT_SUPPORTED"
}

{
  "error": true,
  "message": "<error message>",
  "code": "DEVICE_SIGNER_NOT_SUPPORTED"
}

POST

2025-06-09

wallets

{walletLocator}

signatures

Create Signature

curl --request POST \
  --url https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <x-api-key>' \
  --data '
{
  "params": {
    "chain": "ethereum",
    "message": "Hello, world!",
    "signer": "external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E"
  },
  "type": "message"
}
'

import requests

url = "https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures"

payload = {
    "params": {
        "chain": "ethereum",
        "message": "Hello, world!",
        "signer": "external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E"
    },
    "type": "message"
}
headers = {
    "X-API-KEY": "<x-api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'X-API-KEY': '<x-api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    params: {
      chain: 'ethereum',
      message: 'Hello, world!',
      signer: 'external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E'
    },
    type: 'message'
  })
};

fetch('https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'params' => [
        'chain' => 'ethereum',
        'message' => 'Hello, world!',
        'signer' => 'external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E'
    ],
    'type' => 'message'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "X-API-KEY: <x-api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures"

	payload := strings.NewReader("{\n  \"params\": {\n    \"chain\": \"ethereum\",\n    \"message\": \"Hello, world!\",\n    \"signer\": \"external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E\"\n  },\n  \"type\": \"message\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("X-API-KEY", "<x-api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures")
  .header("X-API-KEY", "<x-api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"params\": {\n    \"chain\": \"ethereum\",\n    \"message\": \"Hello, world!\",\n    \"signer\": \"external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E\"\n  },\n  \"type\": \"message\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://staging.crossmint.com/api/2025-06-09/wallets/{walletLocator}/signatures")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-API-KEY"] = '<x-api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"params\": {\n    \"chain\": \"ethereum\",\n    \"message\": \"Hello, world!\",\n    \"signer\": \"external-wallet:0xB17Ea8d34078424B9d7D126E444d5F2C3CC5c81E\"\n  },\n  \"type\": \"message\"\n}"

response = http.request(request)
puts response.read_body

{
  "approvals": {
    "pending": [
      {
        "quorumApprovals": {
          "pending": [
            {
              "message": "<string>",
              "signer": {
                "address": "<string>",
                "locator": "<string>",
                "type": "api-key"
              }
            }
          ],
          "remaining": 123,
          "submitted": [
            {
              "message": "<string>",
              "signature": "<string>",
              "signer": {
                "address": "<string>",
                "locator": "<string>",
                "type": "api-key"
              },
              "submittedAt": 123
            }
          ],
          "threshold": 123
        },
        "signer": {
          "locator": "<string>",
          "type": "quorum"
        }
      }
    ],
    "required": 123,
    "submitted": [
      {
        "quorumApprovals": {
          "pending": [
            {
              "message": "<string>",
              "signer": {
                "address": "<string>",
                "locator": "<string>",
                "type": "api-key"
              }
            }
          ],
          "remaining": 123,
          "submitted": [
            {
              "message": "<string>",
              "signature": "<string>",
              "signer": {
                "address": "<string>",
                "locator": "<string>",
                "type": "api-key"
              },
              "submittedAt": 123
            }
          ],
          "threshold": 123
        },
        "signer": {
          "locator": "<string>",
          "type": "quorum"
        }
      }
    ]
  },
  "chainType": "aptos",
  "createdAt": 123,
  "id": "<string>",
  "params": {
    "authorizationEntries": "<string>",
    "signer": {
      "address": "<string>",
      "locator": "<string>",
      "type": "api-key"
    }
  },
  "status": "awaiting-approval",
  "type": "auth-entries",
  "walletType": "mpc",
  "completedAt": 123,
  "error": "<unknown>",
  "outputSignature": "<string>"
}

{
  "error": true,
  "message": "<error message>",
  "code": "DEVICE_SIGNER_NOT_SUPPORTED"
}

{
  "error": true,
  "message": "<error message>",
  "code": "DEVICE_SIGNER_NOT_SUPPORTED"
}

Headers

X-API-KEY

string

required

API key required for authentication

x-idempotency-key

string

Unique key to prevent duplicate signature creation

Path Parameters

walletLocator

string

required

A wallet locator can be of the format:

<walletAddress>
email:<email>:<chainType>[:<walletType>][:alias:<alias>] (walletType defaults to 'smart')
userId:<userId>:<chainType>[:<walletType>][:alias:<alias>] (white label user example)
phoneNumber:<phoneNumber>:<chainType>[:<walletType>][:alias:<alias>]
twitter:<handle>:<chainType>[:<walletType>][:alias:<alias>]
x:<handle>:<chainType>[:<walletType>][:alias:<alias>]
me:<chainType>[:<walletType>][:alias:<alias>] (Use when calling from the client side with a client API key)
chainType[:<walletType>]:alias:<alias>

Body

application/json

Message Signature
Typed Data Signature
Auth Entries Signature

Input schema for creating a new signature. The parameters vary based on the signature type.

params

object

required

Parameters for a message signature

Show child attributes

type

enum<string>

required

Available options:

message

Response

The signature has been successfully created.

approvals

object

required

Complete approval data including requirements, pending and submitted signatures

Show child attributes

chainType

enum<string>

required

The blockchain type of the wallet

Available options:

aptos,

evm,

solana,

stellar,

sui

createdAt

required

ISO timestamp when the signature was created

string

required

Unique identifier for the signature

params

Auth entries signature parameters · object

required

Type-specific signature parameters

Auth entries signature parameters
Message signature parameters
Typed data signature parameters

Show child attributes

status

enum<string>

required

Current status of the signature

Available options:

awaiting-approval,

failed,

pending,

success

type

enum<string>

required

The type of signature

Available options:

auth-entries,

message,

typed-data

walletType

enum<string>

required

The wallet type (smart or mpc)

Available options:

mpc,

smart

completedAt

ISO timestamp when the transaction reached finality

error

any

Error message if the signature fails

outputSignature

string

The wallet's output signature of the request

Introduction

Quickstarts ⚡️

Concepts

Guides

API Reference

Create Signature

Headers

Path Parameters

Body

Response