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Transition to the USPS REST API

December 15, 2025 | ,

What is USPS and why is it important?

USPS (United States Postal Service) Shipping is a premium method that sources shipping rates from the USPS API. USPS can calculate domestic and international parcel rates. As of January 25th, 2026, the USPS API Versions 1 and 2 will be retired.

To ensure uninterrupted shipping rate calculations and access to new features, all users must migrate to the latest USPS REST API. This is especially important for WooCommerce merchants using the USPS Shipping Method plugin.

Key Dates

USPS API V1 & V2 Retirement: January 22, 2025(USPS Industry Alert)

WooCommerce Plugin Legacy Web Tools API Retirement: January 25, 2026 (WooCommerce USPS Shipping Method Documentation)

If customers do not update and migrate to the REST API before the Web Tools retirement date (January 25, 2026), live rate calculations for USPS will stop working on their site until they switch to the REST API.

Why Upgrade?

Improved Reliability & Uptime: Enhanced fault tolerance and minimized disruptions.

Faster Performance: Reduced latency and improved data throughput.

Expanded Functionality: Advanced tracking, better address validation, and more accurate rate calculations.

Greater Security: OAuth 2.0 replaces legacy authentication for stronger protection.

New Error Handling: More detailed error codes and responses.

How to Upgrade?

If the client is using an older USPS API version you must ensure to update the WooCommerce USPS Shipping Method Plugin. Make sure that the plugin is updated to version 5.2.5 or higher. This version supports the new REST API and is required for migration.

Make sure you are using version 5.2.5 or higher of the USPS Shipping Method plugin and plan on migrating to the new REST API as soon as possible before January 25, 2026.

For a step-by-step guide on how to upgrade to the new REST API, the following link is very useful Generating Your REST API Keys. This link is from the official WooCommerce documentation and any changes that might appear to the process of upgrading will first appear here, thus we strongly advise to follow the step in that article.

When switching to REST API, we strongly recommend testing the connection on a staging copy of your site before making the change on your live site, as this will help ensure that live rate calculations continue to work as expected during this transition.

If USPS rates stop working, enable Debug Mode and review the API Response in the logs, as that message should explain why service was prematurely disrupted and what is needed to restore access.

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