FAQs

The warning codes that can be returned include:

• 001 - Contract rate not found for request. Published rate returned.
• 002 - Dimensional weight is greater than provided weight. Dimensional rate returned.
• 003 - Collection on Delivery fees paid via cash require an additional Money Order fee of $2.55.
• 003 - Collection on Delivery fees paid via cash require an additional Money Order fee of $3.60.

The API error list is maintained on USPS's GitHub page. You can access the full list here.

The addZPLComments and addImageComments feature is only available in the Testing Environment Endpoint. ZPL Comments will not be returned in the Production Environment Endpoint on Label APIs.

Use the TEM environment with your existing production credentials and accounts. The TEM environment is accessed by appending "-tem" in the base URL of the API call. See example below: 

Example Domestic Labels TEM endpoint: https://apis-tem.usps.com/labels/v3/label

Users that would like to test and run label requests in the TEM environment can do so by initiating the request through a TEM endpoint. 

Note: When generating labels through the TEM environment, labels will be watermarked and will not be processed for payment. 

You need to provide a valid client ID and secret pair.

Sign-in to the API Developer Portal, select Apps then Add App.
When you finish adding an app, the client ID is the 'Consumer Key' and client secret the 'Consumer Secret'.

If you previously have added an app, then copy the Consumer Key and Secret and paste it into your OAuth token request.

If you are experiencing an "Access Denied" error displayed on a page within the USPS Developer, please try the following troubleshooting methods:

• Clearing browser cache
• Clearing browser cookies
• Switch to your browsers "Incognito" mode
• Switch to a different browser 
• Reboot system and log back into the USPS Developer Portal

If you are still experiencing issues, please submit a USPS API service request through the Email Us page.

The default product includes OAuth, Addresses, Domestic Pricing, International Pricing, Locations, Service Standards, Service Standards Files, Shipping Options, UserInfo, and Tracking. To get started with APIs not included in the default or to request a quota increase, please contact us by submitting a USPS API service request on the Email Us page and a representative will assist.

USPS APIs Release Notes can be found on USPS PostalPro website. The Release Notes are updated frequently to notify integrators of forthcoming updates across the USPS APIs catalog. Please view the Release Notes documentation here: USPS APIs Tech Sheets. 

If you have exceeded the quota limit of API calls per hour, please submit a service request on the Email Us page and a representative will assist.

USPS APIs are bundled into consumable packages called API products.
Each API product limits APIs access by time, scope, and quota.
Review the API product documentation to choose the API products that meet the end-user activity and usage needs of your application.
Are you performing a soft launch of your application?  Choose an API product with a limited duration. You may upgrade to a comparable API product later.
Some API products are approved automatically upon request and others require administrative approvals in order to utilize their included APIs.

Please submit a service request on the Email Us page and a representative will assist.

All USPS APIs utilize OAuth, an industry standard, to grant authorized access.

You will be issued a Consumer Key and Secret when you 'Add an App' in the API Developer Portal.