const response = await fetch('https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer em_test_51RxCWJ...vS00p61e0qRE',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    first_name: 'Jane',
    last_name: 'Smith',
    custom_fields: { company: 'NewCorp' }
  })
});

const result = await response.json();

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => 'https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M',
  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([
    'first_name' => 'Jane',
    'last_name' => 'Smith',
    'custom_fields' => ['company' => 'NewCorp']
  ]),
  CURLOPT_HTTPHEADER => [
    'Authorization: Bearer em_test_51RxCWJ...vS00p61e0qRE',
    'Content-Type: application/json'
  ],
]);

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

curl_close($curl);

if ($err) {
  echo "Error cURL #:" . $err;
} else {
  $result = json_decode($response, true);
  print_r($result);
}

import requests

response = requests.post(
    'https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M',
    headers={
        'Authorization': 'Bearer em_test_51RxCWJ...vS00p61e0qRE',
        'Content-Type': 'application/json'
    },
    json={
        'first_name': 'Jane',
        'last_name': 'Smith',
        'custom_fields': {'company': 'NewCorp'}
    }
)

result = response.json()
print(result)

require 'net/http'
require 'json'

uri = URI('https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M')
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true

request = Net::HTTP::Post.new(uri)
request['Authorization'] = 'Bearer em_test_51RxCWJ...vS00p61e0qRE'
request['Content-Type'] = 'application/json'
request.body = {
  first_name: 'Jane',
  last_name: 'Smith',
  custom_fields: { company: 'NewCorp' }
}.to_json

response = http.request(request)
result = JSON.parse(response.body)
puts result

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "net/http"
)

func main() {
    url := "https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M"
    
    data := map[string]interface{}{
        "first_name":    "Jane",
        "last_name":     "Smith",
        "custom_fields": map[string]string{"company": "NewCorp"},
    }
    
    jsonData, _ := json.Marshal(data)
    
    req, _ := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
    req.Header.Set("Authorization", "Bearer em_test_51RxCWJ...vS00p61e0qRE")
    req.Header.Set("Content-Type", "application/json")
    
    client := &http.Client{}
    resp, _ := client.Do(req)
    defer resp.Body.Close()
    
    var result map[string]interface{}
    json.NewDecoder(resp.Body).Decode(&result)
    fmt.Println(result)
}

use reqwest;
use serde_json::{json, Value};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = reqwest::Client::new();
    
    let response = client
        .post("https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M")
        .header("Authorization", "Bearer em_test_51RxCWJ...vS00p61e0qRE")
        .header("Content-Type", "application/json")
        .json(&json!({
            "first_name": "Jane",
            "last_name": "Smith",
            "custom_fields": {"company": "NewCorp"}
        }))
        .send()
        .await?;
    
    let result: Value = response.json().await?;
    println!("{:?}", result);
    
    Ok(())
}

import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.URI;
import java.net.http.HttpRequest.BodyPublishers;

public class UpdateContact {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();
        
        String jsonBody = "{\"first_name\":\"Jane\",\"last_name\":\"Smith\",\"custom_fields\":{\"company\":\"NewCorp\"}}";
        
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M"))
            .header("Authorization", "Bearer em_test_51RxCWJ...vS00p61e0qRE")
            .header("Content-Type", "application/json")
            .POST(BodyPublishers.ofString(jsonBody))
            .build();
        
        HttpResponse<String> response = client.send(request, 
            HttpResponse.BodyHandlers.ofString());
        
        System.out.println(response.body());
    }
}

using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json;

public class UpdateContact
{
    public static async Task Main()
    {
        using (var client = new HttpClient())
        {
            client.DefaultRequestHeaders.Add("Authorization", 
                "Bearer em_test_51RxCWJ...vS00p61e0qRE");
            
            var data = new {
                first_name = "Jane",
                last_name = "Smith",
                custom_fields = new { company = "NewCorp" }
            };
            var json = JsonConvert.SerializeObject(data);
            var content = new StringContent(json, Encoding.UTF8, "application/json");
            
            var response = await client.PostAsync(
                "https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M", content);
            
            var result = await response.Content.ReadAsStringAsync();
            Console.WriteLine(result);
        }
    }
}

curl -X POST https://api.emailit.com/v2/contacts/con_2BxFg7KNqr5M \
  -H "Authorization: Bearer em_test_51RxCWJ...vS00p61e0qRE" \
  -H "Content-Type: application/json" \
  -d '{
    "first_name": "Jane",
    "last_name": "Smith",
    "custom_fields": { "company": "NewCorp" }
  }'

{
  "object": "contact",
  "id": "con_2BxFg7KNqr5M...",
  "email": "john@example.com",
  "first_name": "Jane",
  "last_name": "Smith",
  "custom_fields": { "company": "NewCorp" },
  "unsubscribed": false,
  "audiences": [
    {
      "id": "aud_xxx",
      "name": "Newsletter",
      "subscriber": {
        "id": "sub_xxx",
        "subscribed": true,
        "subscribed_at": "2026-02-10T10:00:00.000000+00:00",
        "unsubscribed_at": null,
        "created_at": "2026-02-10T10:00:00.000000+00:00",
        "updated_at": "2026-02-10T10:00:00.000000+00:00"
      }
    }
  ],
  "created_at": "2026-02-10T10:00:00.000000+00:00",
  "updated_at": "2026-02-12T09:00:00.000000+00:00"
}

{
  "error": "Contacto no encontrado"
}

{
  "error": "Ya existe un contacto con este correo electrónico",
  "existing": {
    "object": "contact",
    "id": "con_...",
    "email": "..."
  }
}