curl --request POST \
  --url https://api.circle.com/v1/w3s/user/sign/message \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-User-Token: <x-user-token>' \
  --data '
{
  "message": "I agree with this transfer",
  "walletId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5",
  "blockchain": "MATIC-AMOY",
  "walletAddress": "0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350",
  "encodedByHex": false,
  "memo": "Transfer USDC to Sam"
}
'

import requests

url = "https://api.circle.com/v1/w3s/user/sign/message"

payload = {
    "message": "I agree with this transfer",
    "walletId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5",
    "blockchain": "MATIC-AMOY",
    "walletAddress": "0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350",
    "encodedByHex": False,
    "memo": "Transfer USDC to Sam"
}
headers = {
    "X-User-Token": "<x-user-token>",
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'X-User-Token': '<x-user-token>',
    Authorization: 'Bearer <token>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    message: 'I agree with this transfer',
    walletId: 'c4d1da72-111e-4d52-bdbf-2e74a2d803d5',
    blockchain: 'MATIC-AMOY',
    walletAddress: '0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350',
    encodedByHex: false,
    memo: 'Transfer USDC to Sam'
  })
};

fetch('https://api.circle.com/v1/w3s/user/sign/message', 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://api.circle.com/v1/w3s/user/sign/message",
  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([
    'message' => 'I agree with this transfer',
    'walletId' => 'c4d1da72-111e-4d52-bdbf-2e74a2d803d5',
    'blockchain' => 'MATIC-AMOY',
    'walletAddress' => '0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350',
    'encodedByHex' => false,
    'memo' => 'Transfer USDC to Sam'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json",
    "X-User-Token: <x-user-token>"
  ],
]);

$response = curl_exec($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://api.circle.com/v1/w3s/user/sign/message"

	payload := strings.NewReader("{\n  \"message\": \"I agree with this transfer\",\n  \"walletId\": \"c4d1da72-111e-4d52-bdbf-2e74a2d803d5\",\n  \"blockchain\": \"MATIC-AMOY\",\n  \"walletAddress\": \"0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350\",\n  \"encodedByHex\": false,\n  \"memo\": \"Transfer USDC to Sam\"\n}")

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

	req.Header.Add("X-User-Token", "<x-user-token>")
	req.Header.Add("Authorization", "Bearer <token>")
	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://api.circle.com/v1/w3s/user/sign/message")
  .header("X-User-Token", "<x-user-token>")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"message\": \"I agree with this transfer\",\n  \"walletId\": \"c4d1da72-111e-4d52-bdbf-2e74a2d803d5\",\n  \"blockchain\": \"MATIC-AMOY\",\n  \"walletAddress\": \"0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350\",\n  \"encodedByHex\": false,\n  \"memo\": \"Transfer USDC to Sam\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.circle.com/v1/w3s/user/sign/message")

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

request = Net::HTTP::Post.new(url)
request["X-User-Token"] = '<x-user-token>'
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"message\": \"I agree with this transfer\",\n  \"walletId\": \"c4d1da72-111e-4d52-bdbf-2e74a2d803d5\",\n  \"blockchain\": \"MATIC-AMOY\",\n  \"walletAddress\": \"0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350\",\n  \"encodedByHex\": false,\n  \"memo\": \"Transfer USDC to Sam\"\n}"

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

{
  "data": {
    "challengeId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5"
  }
}

{
  "data": {
    "challengeId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5"
  }
}

{
  "code": 400,
  "message": "Bad request."
}

{
  "code": 401,
  "message": "Malformed authorization."
}

{
  "code": 404,
  "message": "Not found."
}