curl --request POST \
  --url https://example.com/callback \
  --header 'Content-Type: application/json' \
  --data '
{
  "from": "255701000001",
  "to": "255701000000",
  "channel": "whatsapp",
  "user_name": "James",
  "transaction_id": "12345",
  "message_type": "text",
  "text": "Yes, I would like more info"
}
'

import requests

url = "https://example.com/callback"

payload = {
    "from": "255701000001",
    "to": "255701000000",
    "channel": "whatsapp",
    "user_name": "James",
    "transaction_id": "12345",
    "message_type": "text",
    "text": "Yes, I would like more info"
}
headers = {"Content-Type": "application/json"}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    from: '255701000001',
    to: '255701000000',
    channel: 'whatsapp',
    user_name: 'James',
    transaction_id: '12345',
    message_type: 'text',
    text: 'Yes, I would like more info'
  })
};

fetch('https://example.com/callback', 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://example.com/callback",
  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([
    'from' => '255701000001',
    'to' => '255701000000',
    'channel' => 'whatsapp',
    'user_name' => 'James',
    'transaction_id' => '12345',
    'message_type' => 'text',
    'text' => 'Yes, I would like more info'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($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://example.com/callback"

	payload := strings.NewReader("{\n  \"from\": \"255701000001\",\n  \"to\": \"255701000000\",\n  \"channel\": \"whatsapp\",\n  \"user_name\": \"James\",\n  \"transaction_id\": \"12345\",\n  \"message_type\": \"text\",\n  \"text\": \"Yes, I would like more info\"\n}")

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

	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://example.com/callback")
  .header("Content-Type", "application/json")
  .body("{\n  \"from\": \"255701000001\",\n  \"to\": \"255701000000\",\n  \"channel\": \"whatsapp\",\n  \"user_name\": \"James\",\n  \"transaction_id\": \"12345\",\n  \"message_type\": \"text\",\n  \"text\": \"Yes, I would like more info\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://example.com/callback")

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

request = Net::HTTP::Post.new(url)
request["Content-Type"] = 'application/json'
request.body = "{\n  \"from\": \"255701000001\",\n  \"to\": \"255701000000\",\n  \"channel\": \"whatsapp\",\n  \"user_name\": \"James\",\n  \"transaction_id\": \"12345\",\n  \"message_type\": \"text\",\n  \"text\": \"Yes, I would like more info\"\n}"

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