Accurate Multi-Carrier Real-Time Shipping Rates, Built In! Shippingcalc by Auctioninc in X-Cart 5.
Starting from 5.2.5, this module is enabled by default. You're starting to get rates from USPS, UPS, DHL and FedEX without an account there! After the free 30 days trial period is over, or if you decide to get access to premium subscription-based features earlier, follow the "signup" link to provide your personal and business details and get an account.