Follow these steps and start using USPS APIs:

1. API Catalog

Browse through USPS APIs and download the OpenAPI standard specifications if you choose.

2. Log In

Log in to the USPS Developer Portal USPS Developer Portal using your USPS business account credentials.

New to USPS.com? You can create a USPS business account if you do not already have one by following the directions, or directly https://catpx-custreg.usps.com/entreg/RegistrationAction_input.

3. Create an App

Register an application which you will use to consume USPS APIs.

Click the Apps button from the Menu Bar and complete the following steps to create an App:

  1. Click "Add app" button
  2. Enter "App Name" for your application (required)
  3. Enter "Callback URL" (optional)
  4. Check the box to accept Terms and Conditions, and Privacy Policy
  5. Enter "Description" (optional)
  6. Select the APIs Available (required)
  7. Click "ADD APP" Button

4. Retrieve your Consumer Key and Secret 

Select the application you just registered and copy your Consumer Key and Consumer Secret from the credentials section. These credentials are required for generating OAuth tokens.

5. Authorize Application to Access Protected Information Resources

The Customer Onboarding Portal ensures that your USPS business account is complete. You will also grant access to your account information to the application you just registered.  This provides additional information that is used to access several USPS APIs.

Navigate to the USPS Customer Onboarding Portal to authorize the client application you registered in order to access your information resources shared with the USPS, such as payment accounts, permits, CRID's, MID's, and subscriptions.

This step is required to access all Version 3 APIs.

6. Generate your OAuth 2.0 Access Tokens

All USPS APIs require an OAuth 2.0 access token to be conveyed in the Authorization header, using the Bearer token scheme. To retrieve your Bearer Token, you will need the consumer key (client_id) and consumer secret (client_secret) from the app you created. 

The OAuth2 V1 API is required for all versions 1 and 2 APIs; you will also need the customer registration ID (customer_registration_id) and mailer ID (mailer_id) in addition to the consumer key and consumer secret for the appropriate environment. Review the OpenAPI specification here.

The OAuth2 V3 API is required for version 3 APIs. Review the OpenAPI specification here.

7. Try Out USPS APIs

Review the published APIs through the API Catalog page on the USPS Developer Portal.  Example Postman requests and Curl commands for any API you would like to try out and execute are available on USPS Github.

Note: If you want to use the Label API it requires additional approval and configuration.  The Label API requires you to be enrolled in USPS Ship for both outbound and return labels and have an Enterprise Payment Account or a Permit.  If you are interested in using the Label API or have questions, please use the Contact information below.

Contact Us:

If you have questions, please contact us at APISupport@usps.gov. In your email include the following information:

  • Your Name
  • Contact Phone Number
  • Developer Portal Username
  • URL being called (api.usps.com or api-cat.usps.com)
  • Customer Registration Id (CRID)
  • Mailer Id (MID)
  • Developer Portal App Name

**Do not include consumer key (client_id) and or consumer secret (client_secret)