curl --request POST \
  --url https://api.cal.com/v2/events/{uuid}/registrations/{registrationId}/check-in \
  --header 'Authorization: <authorization>'

import requests

url = "https://api.cal.com/v2/events/{uuid}/registrations/{registrationId}/check-in"

headers = {"Authorization": "<authorization>"}

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

print(response.text)

const options = {method: 'POST', headers: {Authorization: '<authorization>'}};

fetch('https://api.cal.com/v2/events/{uuid}/registrations/{registrationId}/check-in', 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/events/{uuid}/registrations/{registrationId}/check-in",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_HTTPHEADER => [
    "Authorization: <authorization>"
  ],
]);

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

curl_close($curl);

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

package main

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

func main() {

	url := "https://api.cal.com/v2/events/{uuid}/registrations/{registrationId}/check-in"

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

	req.Header.Add("Authorization", "<authorization>")

	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/events/{uuid}/registrations/{registrationId}/check-in")
  .header("Authorization", "<authorization>")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.cal.com/v2/events/{uuid}/registrations/{registrationId}/check-in")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = '<authorization>'

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

{
  "status": "success",
  "data": {
    "kind": "checked_in",
    "registration": {
      "id": "<string>",
      "name": "<string>",
      "email": "<string>",
      "status": "PENDING_APPROVAL",
      "rsvpResponse": "YES",
      "createdAt": "2023-11-07T05:31:56Z",
      "phoneNumber": "<string>",
      "responses": {},
      "locationId": "<string>",
      "checkedInAt": "2023-11-07T05:31:56Z",
      "checkedInByUserId": 123
    },
    "checkedInAt": "2023-11-07T05:31:56Z",
    "status": "PENDING_APPROVAL"
  }
}