curl --request POST \
  --url https://api.cal.com/v2/bookings/{bookingUid}/attendees \
  --header 'Authorization: <authorization>' \
  --header 'Content-Type: application/json' \
  --header 'cal-api-version: <cal-api-version>' \
  --data '
{
  "name": "John Doe",
  "timeZone": "America/New_York",
  "email": "john.doe@example.com",
  "phoneNumber": "+919876543210",
  "language": "it"
}
'

import requests

url = "https://api.cal.com/v2/bookings/{bookingUid}/attendees"

payload = {
    "name": "John Doe",
    "timeZone": "America/New_York",
    "email": "john.doe@example.com",
    "phoneNumber": "+919876543210",
    "language": "it"
}
headers = {
    "cal-api-version": "<cal-api-version>",
    "Authorization": "<authorization>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'cal-api-version': '<cal-api-version>',
    Authorization: '<authorization>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    name: 'John Doe',
    timeZone: 'America/New_York',
    email: 'john.doe@example.com',
    phoneNumber: '+919876543210',
    language: 'it'
  })
};

fetch('https://api.cal.com/v2/bookings/{bookingUid}/attendees', 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.cal.com/v2/bookings/{bookingUid}/attendees",
  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([
    'name' => 'John Doe',
    'timeZone' => 'America/New_York',
    'email' => 'john.doe@example.com',
    'phoneNumber' => '+919876543210',
    'language' => 'it'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: <authorization>",
    "Content-Type: application/json",
    "cal-api-version: <cal-api-version>"
  ],
]);

$response = curl_exec($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.cal.com/v2/bookings/{bookingUid}/attendees"

	payload := strings.NewReader("{\n  \"name\": \"John Doe\",\n  \"timeZone\": \"America/New_York\",\n  \"email\": \"john.doe@example.com\",\n  \"phoneNumber\": \"+919876543210\",\n  \"language\": \"it\"\n}")

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

	req.Header.Add("cal-api-version", "<cal-api-version>")
	req.Header.Add("Authorization", "<authorization>")
	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.cal.com/v2/bookings/{bookingUid}/attendees")
  .header("cal-api-version", "<cal-api-version>")
  .header("Authorization", "<authorization>")
  .header("Content-Type", "application/json")
  .body("{\n  \"name\": \"John Doe\",\n  \"timeZone\": \"America/New_York\",\n  \"email\": \"john.doe@example.com\",\n  \"phoneNumber\": \"+919876543210\",\n  \"language\": \"it\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.cal.com/v2/bookings/{bookingUid}/attendees")

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

request = Net::HTTP::Post.new(url)
request["cal-api-version"] = '<cal-api-version>'
request["Authorization"] = '<authorization>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"name\": \"John Doe\",\n  \"timeZone\": \"America/New_York\",\n  \"email\": \"john.doe@example.com\",\n  \"phoneNumber\": \"+919876543210\",\n  \"language\": \"it\"\n}"

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

{
  "status": "success",
  "data": {
    "name": "John Doe",
    "email": "john@example.com",
    "displayEmail": "john@example.com",
    "timeZone": "America/New_York",
    "absent": false,
    "id": 251,
    "bookingId": 313,
    "language": "en",
    "phoneNumber": "+1234567890"
  }
}