api_test.php

<?php
require 'app/Mage.php';

Mage::app('admin')->setUseSessionInUrl(false);

try {
    $client = new Zend_Soap_Client('http://local.magento/api/soap/?wsdl');
    
    // login
    $sessionId = $client->login('user', 'pass');
    
    // get product info
    $product = $client->call($sessionId, 'product.info', 'PRODUCT_SKU_OR_ID');
    
    var_dump($product);
} catch (Exception $e) {
    // log the error
    Mage::log($e->getMessage(), Zend_Log::ERR);
}