Hi,
USPS decided to retire their Web Tools API last year:
Web Tools APIs Retired January 25, 2026
Migrate NOW to USPS APIs
The USPS Web Tools API platform was retired on January 25, 2026 and service disruptions are underway. Platform support is sunsetting and availability may be degraded or interrupted at any time. To avoid service disruptions, migrate now to the new USPS APIs. The functional equivalents of the Web Tools APIs are now available in the USPS API Catalog: USPS APIs Developer Portal.
www.usps.com/business/web-tools-apis/
Of course, the new API is completely different from the previous one. So a whole new plugin needed to be developed last year for this new API. Thus, we worked hard on this and it's been more than 9 months that we released a new plugin for USPS with regular updates to it since then based on the feedback of merchants migrating ahead of the API termination :
www.hikashop.com/marketplace/product/290-usps.html
If you're using the old plugin, you'll have to migrate to the new one to be able to continue connecting your HikaShop with USPS.