Универсальный обработчик форм

<?php

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => 'https://octane.pushka.biz/api/handler-form/12345/general',
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 0,
  CURLOPT_FOLLOWLOCATION => true,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => 'POST',
  CURLOPT_POSTFIELDS => array(
    'contactPhone' => '375296117699',
    'contactName' => 'Василий Иванович',
    'leadName' => 'Супер сделка',
    'lead_cf_33333' => 'ВИП',
    'contact_cf_22222' => 'Согласен',
    'tags' => 'ВАЖНАЯ,СРОЧНО'
  ),
));

$response = curl_exec($curl);
curl_close($curl);
echo $response;

<?php
$client = new Client();
$options = [
  'multipart' => [
    [
      'name' => 'contactPhone',
      'contents' => '375296117699'
    ],
    [
      'name' => 'contactName',
      'contents' => 'Василий Иванович'
    ],
    [
      'name' => 'leadName',
      'contents' => 'Супер сделка'
    ],
    [
      'name' => 'lead_cf_33333',
      'contents' => 'ВИП'
    ],
    [
      'name' => 'contact_cf_22222',
      'contents' => 'Согласен'
    ],
    [
      'name' => 'tags',
      'contents' => 'ВАЖНАЯ,СРОЧНО'
    ]
]];
$request = new Request('POST', 'https://octane.pushka.biz/api/handler-form/12345/general');
$res = $client->sendAsync($request, $options)->wait();
echo $res->getBody();

var formdata = new FormData();
formdata.append("contactPhone", "375296117699");
formdata.append("contactName", "Василий Иванович");
formdata.append("leadName", "Супер сделка");
formdata.append("lead_cf_33333", "ВИП");
formdata.append("contact_cf_22222", "Согласен");
formdata.append("tags", "ВАЖНАЯ,СРОЧНО");

var requestOptions = {
  method: 'POST',
  body: formdata,
  redirect: 'follow'
};

fetch("https://octane.pushka.biz/api/handler-form/12345/general", requestOptions)
  .then(response => response.text())
  .then(result => console.log(result))
  .catch(error => console.log('error', error));

var form = new FormData();
form.append("contactPhone", "375296117699");
form.append("contactName", "Василий Иванович");
form.append("leadName", "Супер сделка");
form.append("lead_cf_33333", "ВИП");
form.append("contact_cf_22222", "Согласен");
form.append("tags", "ВАЖНАЯ,СРОЧНО");

var settings = {
  "url": "https://octane.pushka.biz/api/handler-form/12345/general",
  "method": "POST",
  "timeout": 0,
  "processData": false,
  "mimeType": "multipart/form-data",
  "contentType": false,
  "data": form
};

$.ajax(settings).done(function (response) {
  console.log(response);
});

curl --location 'https://octane.pushka.biz/api/handler-form/12345/general' \
--form 'contactPhone="375296117699"' \
--form 'contactName="Василий Иванович"' \
--form 'leadName="Супер сделка"' \
--form 'lead_cf_33333="ВИП"' \
--form 'contact_cf_22222="Согласен"' \
--form 'tags="ВАЖНАЯ,СРОЧНО"'