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OSM Guide

Want to use EasyPost to ship with OSM? This guide will break down all the necessary steps to make it happen.

If you haven't generated your first shipping label with EasyPost, we recommend reading our Getting Started Guide to learn how.

Setting Up Your OSM Account

Follow the instructions below to start shipping with OSM through EasyPost. If you have not created an EasyPost account, sign up now!

  • Register for a OSM shipper account:
    • Register for an OSM shipper account on their website, and OSM will contact you.
    • Let them know you will be using EasyPost's API to purchase labels. You will need to obtain the following account credentials from OSM:
      • Account Number
      • Mailer ID
      • Facility Code/Cost Center ID for manifesting (optional)
      • Company Name (your company or business name)
      • SFTP Account
  • Link your OSM shipper account to EasyPost using our dashboard:
    • Log in to your EasyPost account and navigate to the Carrier Accounts page.
    • Add your OSM carrier account credentials to reflect their service levels in our shipping API.
    • Begin purchasing labels through the EasyPost shipping API!
  • Add your OSM carrier shipper account to EasyPost using an API OSM account structure example below:

Service Levels

OSM delivers 6 days per week (Mon-Sat). The service levels through EasyPost include:

Transit Time
Max Dimensions (inches)
Max Weight (ounces)

OSM supports the following predefined packages:

Predefined Package
Dimensions (inches)
Weight (ounces)

Supported Options

Label Formats and Sizes

When a customer is providing labels to OSM for validation during onboarding, those MUST be in ZPL format and cannot ever be converted to or from any other format, otherwise they will fail. OSM Worldwide recommends Zebra Models S4M and GK420d.

OSM Supports a 4x6 label size.

Advanced Options & Returns

Return label types are supported by OSM. OSM supports a separate service level for returns. Returns are discounted from standard ground service levels. There are no unique rules required to rate and purchase a return label.


EasyPost will return 1 cent rates by default once you set up your OSM account with us. This means that although you will see a 1 cent rate on your shipment, OSM will charge you the appropriate amount for postage via their billing system.

An OSM Worldwide rep can provide you with a rate card that will show you what rates you can expect to pay OSM given shipment parameters (package size/weight, location, etc.). EasyPost is not automatically privy to these rates, so when you first create an OSM account you will need to obtain your custom rate card from OSM. Once you have obtained your rate card, contact support@easypost.com for help installing your rate card.

Generating Shipping Labels

Generating shipping labels for OSM is the same as generating them for any other carrier with EasyPost. See our Getting Started Guide for help generating your first shipping label.

Manifests, Drop Offs and Pickups


Manifesting is supported AND required with OSM. All label purchases must be manifested. OSM archives shipments that were purchased over 120 days ago, and those shipment labels can no longer be manifested. Labels purchased up to 119 days ago can be manifested, but this is not recommended. Users should know that it is best practice to manifest their shipment labels within 10 days of purchase.


OSM supports pickups at the customer's facility. OSM can support pickups for any customer based on their agreement. Regular pickups can be arranged with the OSM team during the registration process; however, cannot be scheduled through the EasyPost API.

Tracking Your OSM Packages

Tracking statuses are available for all OSM shipments. Creating a Tracker for OSM is identical to creating a tracker with any other carrier through EasyPost.

Take a look at our Tracking Guide for support in creating your first Tracker.

Need More Info About OSM?

Our Carrier Metadata endpoint can programatically return information about OSM including service levels, predefined packages, supported features, and shipment options.

Use this information to quickly integrate with OSM or make educated decisions about your carrier mix. You can also use the Carrier Metadata endpoint to retrieve information about all the carriers on the EasyPost platform.

Talk to a Shipping Expert

Any questions about how to start shipping with OSM through the EasyPost API?