Connect USPS

Create a USPS Developer Portal app, copy Consumer Key and Secret, then connect in Net3000.

Connect USPS so Storefront3000 can calculate live shipping rates at checkout.

In Net3000 admin, open Integrations → USPS (/apis/Usps).

Open the USPS Developer Portal

Sign in at developers.usps.com with your USPS Business / Customer Onboarding credentials.
Create an app

Open Apps (or My Apps) → Add App. Enter an app name, accept the terms, select the API product you need (for example Public Access I; add TEM if you will test), then create the app.
Copy Consumer Key and Consumer Secret

Open the app credentials / Approved section and copy the Consumer Key (client id) and Consumer Secret (client secret).
Paste into Net3000

Open /apis/Usps, enter Consumer Key and Consumer Secret, then click Save.
Verify rates at checkout

Place a test order in Storefront3000 and confirm live USPS rates appear during checkout.

Talk to the team behind the docs.