<?php
//$url = 'https://api.mercadolibre.com/sites/MLB/search/';
$url = 'https://api.mercadolibre.com/sites/MLB/search?category=MLB1648';

$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_CAINFO, getcwd() . DIRECTORY_SEPARATOR . 'cacert.pem');

$output = curl_exec($curl);
curl_close($curl);

header('Content-Type: application/json');
echo $output;

The file cacert.pem should be downloaded at link and placed in the same folder as the above script .

NOTE: When using the Free Market API, specify MLB to fetch data in the Brazilian version of the site. MLA refers to the Argentine version.

You can also create a function to make it easier:

<?php

function get($url) {
    $curl = curl_init();
    curl_setopt($curl, CURLOPT_URL, $url);
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, true);
    curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 2);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_CAINFO, getcwd() . DIRECTORY_SEPARATOR . 'cacert.pem');

    $output = curl_exec($curl);
    curl_close($curl);

    return $output;
}

header('Content-Type: application/json');

// Obtém produtos da categoria "Informática"
echo get('https://api.mercadolibre.com/sites/MLB/search?category=MLB1648');

// Obtém as categorias do site;
echo get('https://api.mercadolibre.com/sites/MLB/categories');

// Faz uma busca com a palavra-chave "pendrive"
echo get('https://api.mercadolibre.com/sites/MLB/search?q=pendrive');

See also:

• cURL PHP Library

• Free Market API Documentation