• What APIs are included in the default product for my App?

    The default product includes OAuth, Addresses, Service Standards, International Pricing, Domestic Pricing, and Shipping Options, each with a quota of 60 calls per hour. To get started with APIs not included in the default or to request a quota increase, USPS will need additional information. Please complete the Registration for API Access form here: USPS APIs Quota Form 

  • I received a ‘429' exceeded quota limit error. How do I resolve this?

    If you have exceeded the quota limit of API calls per hour, please complete and submit the USPS APIs Quota Form to get access to additional APIs or get a higher quota limit. Note: You must be logged in to your USPS Developer account in order to submit the form. Any incomplete or missing information will delay your request.

  • What do I need to integrate my application with USPS APIs?

    Most APIs require your business to have credentials issued through the USPS Customer Registration system.

    Also, several APIs may require a payment account to be established.

    See Application Onboarding Procedures for a full description of the steps involved in setting up your accounts.

  • I get an 'invalid customer credentials' failure when I try to request an OAuth token. What am I doing wrong?

    You need to provide a valid Customer Registration ID and Mailer ID pair in order for a token to be issued.

    Contact the Business System Administrator of your Customer Registration account to determine the pair to use based on your location.

    Use the pair based on your location and sender.

  • I get an 'invalid client credentials' failure when I try to request an OAuth token.  What am I doing wrong?

    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.

  • What is the difference between an API and an API Product?

    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.

  • I’m not getting the expected response. Who do I contact?

    Please contact USPS at APISupport@usps.gov.

  • Where do I go to request API keys?

    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.