Description

The Stamps.com API addon connects your WooCommerce store to the Stamps.com service to generate USPS shipping labels directly from the dashboard, pulling real USPS rates at checkout based on the cart’s ZIP code, weight, and dimensions. It is aimed at those who sell physical products through WooCommerce with shipping in the US and need to print official postage without switching between systems, keeping tracking numbers and costs unified in each order.

Key Features of Stamps.com API

  • Live USPS quoting
    Queries the Stamps.com API and displays real shipping rates on the checkout page.
  • Calculation by weight and dimensions
    Uses product weight and measurements from the cart to return accurate rates per package.
  • Domestic and international service support
    Covers USPS options for shipments within the US and dispatches abroad.
  • Linked Stamps.com account
    Authenticates with your Stamps.com account credentials to validate contracted rates.
  • Native integration with Shipping Zones
    Appears as a configurable shipping method in WooCommerce delivery zones.

Benefits of Stamps.com API

  • Shipping costs that match the official postage
    Reduces losses from underestimated shipping by mirroring the official USPS rate on the order.
  • Fewer clicks between sale and fulfillment
    Centralizes quoting and orders in WooCommerce without moving data to spreadsheets or other dashboards.
  • Checkout confidence
    Shoppers see the real shipping cost before paying, reducing cart abandonment due to uncertain shipping fees.
  • Operational scalability
    Keeps automatic quoting even as SKUs, served regions, and weight variations grow.

Who Is Stamps.com API For?

  • Those who sell physical products through WooCommerce and ship via United States Postal Service.
  • You who already have an active Stamps.com account and want to bring those rates directly into the cart.
  • Those who ship dozens of orders per week and need to cut manual quoting time between systems.
  • Those running dropshipping or niche e-commerce with combined domestic and international shipments.

How to Download Stamps.com API

The Stamps.com API is available for download here at Ultrapack. After downloading the .zip file, install it in Plugins > Add New > Upload Plugin, select the file, and activate it. The method will appear in WooCommerce > Settings > Shipping, ready to receive your Stamps.com account credentials.

The addon solves a specific pain point of e-commerce with US-based shipping: quoting reliable freight without keeping parallel tabs open during order fulfillment. By bringing the USPS rate directly into WooCommerce, the store owner standardizes shipping charges, closes the order with the correct amount, and frees the operation to focus on packing and dispatch rather than postage calculation.

Frequently asked questions

Is WooCommerce Stamps.com API GPL-licensed?

Yes. WooCommerce Stamps.com API is distributed under the GPL (GNU General Public License). You may legally use, modify and redistribute it on as many sites as you want.

Can I use WooCommerce Stamps.com API on multiple sites?

Yes. You can install WooCommerce Stamps.com API on as many sites as you want. Only automatic updates through Ultrapack Auto Updater have a limit: from 3 to 80 sites, depending on the plan.

How much does WooCommerce Stamps.com API cost at Ultrapack?

WooCommerce Stamps.com API costs US$2.99 as a single purchase, and it is also included in the subscription plans starting at US$12/mo (VIP I).

Does WooCommerce Stamps.com API include updates?

Yes. The current version of WooCommerce Stamps.com API is 2.3.7, published at Ultrapack on Sep 10, 2026. Subscribers update straight from the WordPress dashboard with UAU (Ultrapack Auto Updater).

Is WooCommerce Stamps.com API scanned before publication?

Yes. Every version of WooCommerce Stamps.com API goes through a malware scan (ClamAV and YARA rules, at UltraHub) before it is published.

What are the requirements for the plugin WooCommerce Stamps.com API?

Requires WordPress 7.0 or higher and PHP 7.4 or higher. Tested up to WordPress 7.1.