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USPS (Stamps.com) Carrier Guide

Stamps.com with ShipEngine provides access to USPS domestic and international shipping services for packages originating in the United States.

This guide provides developers the details needed to build USPS shipping capabilities using a Stamps.com account into your ShipEngine workflows.

Requirements

PropertyTypeRequired?
usernamestringrequired
passwordstringrequired

Connect Account

You can connect a Stamps.com account using the POST method to the /v1/conections/carriers/ endpoint, or via the ShipEngine Dashboard.

For instructions on connecting a Stamps.com via the ShipEngine dashboard, go to our Stamps.com help article.

Connect via Endpoint

carrier_name: stamps_com

POST /v1/connections/carriers/:carrier_name

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POST /v1/connections/carriers/stamps_com HTTP/1.1
Host: api.shipengine.com
API-Key: __YOUR_API_KEY_HERE__
ontent-Type: application/json
{
"username": "myusername",
"password": "123456789",
}

A successful connection will return a response with the carrier_id, which you'll use for any requests for this account going forward.

Rates

Use the rates endpoint to fetch estimated rates for Stamps.com-provided services. See our Calculate Shipping Costs page for details about rate shopping with ShipEngine.

Service Details

Available Stamps.com services are provided below, which include both USPS and GlobalPost services. Please note that carriers may update their available services at any time. To ensure you are always using valid services, you can use the list carrier services endpoint at any time.

USPS Domestic Services

ServiceTransit TimeMaximum Dimensions (LxWxH)Max WeightService Code
USPS Ground Advantage*2-5 days22" x 18" x 15"70 lbsusps_ground_advantage
USPS Priority Mail1-3 daysvaries by package type70 lbsusps_priority_mail
USPS Priority Mail Express1-2 daysL x 2xW x H cannot exceed 108"70 lbsusps_priority_mail_express
Media Mail2-9 daysL x 2xW x H cannot exceed 108"70 lbsusps_media_mail

*In 2023, USPS Ground Advantage replaced both USPS First Class Package and Parcel Select Ground services.

USPS International Services

ServiceTransit TimeMaximum DimensionsMax WeightService Code
USPS First Class Mail Intl7-21 daysL x 2xW x H cannot exceed 136"64 ozusps_first_class_mail_international
USPS Priority Mail Intl6-10 daysL x 2xW x H cannot exceed 108"70 lbsusps_priority_mail_international
USPS Priority Mail Express Intl3-5 daysL x 2xW x H cannot exceed 108"70 lbsusps_priority_mail_express_international

GlobalPost Services

For all GlobalPost services, transit time will vary depending on the destination country.

ServiceMax WeightService Code
GlobalPost Economy Intl4.4 lbsglobalpost_economy
GlobalPost Standard Intl70 lbsglobalpost_priority
GlobalPost Plus66 lbsgp_plus
GlobalPost SmartSaver Economy Intl4.4 lbsglobalpost_economy_smart_saver
GlobalPost SmartSaver Standard Intl70 lbsglobalpost_priority_smart_saver
GlobalPost Plus SmartSaver66 lbsglobalpost_plus

Return Services

Stamps.com supports returns using any domestic service. Review the Return Shipping Labels page for details on creating return labels with ShipEngine.

Packages

The following carrier package types are available for CarrierName services:

Package NameAPI CodePackage Details
Medium Flat Rate Boxmedium_flat_rate_boxDomestic and international
Flat Rate Envelopeflat_rate_envelopeDomestic and international
Small Flat Rate Boxsmall_flat_rate_boxDomestic and international
Large Flat Rate Boxlarge_flat_rate_boxDomestic and international
Flat Rate Padded Envelopeflat_rate_padded_envelopeDomestic and international
Flat Rate Legal Envelopeflat_rate_legal_envelopeDomestic and international

Adding Shipment Insurance

Stamps.com supports adding carrier insurance to your shipments.

Review the Parcel Insurance page for details on adding shipment insurance with ShipEngine.

Label Support

  • Label sizes: 4" x 6"
  • Label formats: PDF, ZPL

Label Reference Fields

Label messages are supported for domestic shipments only. You can use all three label reference fields.

Multi-Package Labels

USPS does not support multi-package shipments at this time.

Label Branding

Stamps.com supports adding a custom label image to your labels. See our Create Custom Shipping Labels page for details.

Voiding Labels

Stamps.com supports voiding labels using ShipEngine, but it must be done within 28 days of label creation.

See our Void a Label page for details about voiding labels with ShipEngine.

Paperless Labels

USPS supports paperless labels with their services. This means you can generate a QR code for your customer and they can take that QR code to be scanned at participating USPS locations, who will then print the label for them.

Review our paperless labels page for details on how to generate a QR code instead of a printable label. Currently this supports the qr_code value for the display_scheme property.

Example QR Code

USPS QR Code

Customer Communications

Using paperless labels might be a new experience for your customers. The USPS suggests sending out an email with the QR code label to help educate your customer on what they need to do to ship their package.

The email containing the QR Code should also include instructions on how to find participating USPS Post Offices by visiting https://tools.usps.com/find-location.htm?locationType=po&serviceType=lbroretail&address=18702, where the value of the address parameter is customer's ZIP Code (such as 18702 in this example). The USPS Retail Associate at that location's Retail Counter will scan the QR Code and print the shipping label, affix it to the package, and provide a receipt.

If the customer has access to a printer, they may choose instead to print the label directly at https://tools.usps.com/label-broker.htm?LabelID=XYZZYPJK&zip=18702, where XYZZYPJK is the Label ID returned by ShipEngine, and 18702 is the ship_from postal_code.

Customs Declarations

Customs declarations for GlobalPost and GAP labels are submitted to the carrier electronically. See our International Shipments page for details about shpping internationally via ShipEngine.

Delivery Confirmation

Confirmation TypeAPI CodeDescription
No confirmationnoneDefault. When no delivery confirmation is requested.
DeliverydeliveryFor general delivery confirmation.
SignaturesignatureA signature is required to complete the delivery.
Adult Signatureadult_signatureAn adult signature is required for the shipment to be delivered.
Restricted deliveryrestricted_delivery

Signature and Adult Signature confirmation types are not supported for international shipments.

See our Delivery Confirmation page for more details about using the confirmation property.

Advanced Options

Stamps.com supports certain advanced options, which you can add to the shipment object when creating a shipment or label.

OptionNameDefault ValueDescription
Non Machinablenon_machinablefalseIndicates that the package cannot be processed through USPS sorting machines.
Dangerous Goodsdangerous_goodsfalseIndicates this shipment contains dangerous goods

To ensure you always have the most up-to-date information about a carrier's advanced options, use the list carrier options call.

Manifests

USPS supports creating manifests (called SCAN forms) via ShipEngine. If you plan to create a USPS SCAN form, you must manifest your day's shipments by 9pm local time.

See our Manifests page for more details about creating manifests with ShipEngine.

Scheduling Pickups

USPS supports scheduling pickups via ShipEngine. Pickups can only be scheduled one day in advance. For example, if you schedule a pickup on the 5th for the 7th, the pickup date scheduled by Stamps.com will be the 6th.

See our Schedule a Carrier Pickup page for more details about scheduling pickups using ShipEngine.

Service Points (PUDO)

USPS does not support shipping to service points.

Tracking

ShipEngine's integration with Stamps.com supports receiving tracking updates. Review our ​Track a Package guides​​ for details on tracking with the ShipEngine API.

Disconnecting Your Stamps.com Account

See the Disconnect section in our Delete a Carrier page for the process of deleting or disconnecting a carrier from ShipEngine.