Sign in Subscribe

USPS API Migration Guide: Implementing OAuth 2.0 for European Shippers Before January 2026 Without Breaking Your TMS

USPS API Migration Guide: Implementing OAuth 2.0 for European Shippers Before January 2026 Without Breaking Your TMS

The USPS Web Tools API platform will be retired on January 25, 2026, marking the end of an era for European shippers who rely on USPS for cross-border shipping. Continued use of this API is subject to disruptions starting in July 2025, meaning you have less than a year to complete your migration without facing service interruptions.

The migration affects millions of shipments from European manufacturers, wholesalers, and retailers who depend on USPS for affordable US delivery. Unlike rate shopping or simple tracking integrations, this requires a complete technical overhaul of your carrier connectivity infrastructure.

Understanding the USPS API Migration Timeline and Impact

This deadline is in addition to the Web Tools label API migration and retirement that went into effect July 14, 2024. USPS has already shown they're serious about these deadlines by successfully retiring the label API functionality last year. As published in the February 6, 2025 Industry Alert, the Web Tools API platform will be retired on January 25, 2026. To avoid any service disruptions, we encourage you to migrate to the new USPS APIs as soon as possible.

The pattern mirrors what we've seen with other major carriers. From June 5, 2023, no new access keys will be distributed, and post-June 3, 2024, any transaction with UPS will mandate this new OAuth security model. Developers have until May 15, 2024 to adopt the improved FedEx API, at which point previous SOAP APIs will become completely inaccessible. USPS is following a similar playbook with a longer timeline.

For European shippers, this creates unique challenges. Your US-bound shipments might represent 20-40% of your total volume, but USPS integration complexity often gets deprioritized compared to local carriers like DPD or DHL. Both carriers have since moved their deadlines to August and September, which tells you what a challenge this has been for most shipper companies to comply with. USPS learned from UPS and FedEx migration difficulties and provided a longer runway.

Technical Differences: Web Tools vs. New USPS APIs

The technical shift is substantial. The Web Tools API credentials are not compatible with the new USPS API platform. To use the new USPS APIs, you must generate entirely new credentials and authentication flows.

The new USPS APIs (https://developers.usps.com) offer modernized security and authentication methods via OAuth 2.0, more product and payment options, webhooks push notifications, and improved performance. But this comes with integration complexity.

Here's what changes:

  • Authentication: Simple User ID becomes OAuth 2.0 access token to be conveyed in the 'Authorization' header, using the 'Bearer' token scheme
  • Request Format: XML requests transform to JSON REST endpoints
  • Token Management: OAuth token is required which will enable access to USPS APIs and is valid for 8 hours
  • Endpoint Structure: To generate your OAuth token in TEM, configure your API endpoint to https://apis-tem.usps.com/oauth2/v3/token. For PROD, configure your API endpoint to https://apis.usps.com/oauth2/v3/token

OAuth 2.0 Implementation for Carrier Connectivity

The OAuth 2.0 client credentials grant type is the primary OAuth flow supported. The "client_id" value is your Consumer Key. The "client_secret" value is your Consumer Secret.

Unlike Web Tools' static credentials, OAuth requires active token management. Access tokens will expire, requiring applications to periodically check the expiration time and get new ones. Your integration needs automated token refresh logic, not just a one-time setup.

Modern TMS providers like Cargoson, nShift, and FreightPOP already handle OAuth token lifecycle management natively. If you're using one of these platforms, your migration path is simpler. For custom integrations, you'll need to build token refresh workflows from scratch.

Note: Label APIs require an additional Payment token valid for 8 hours which is generated via the Payments API. This adds another layer of complexity for label generation workflows.

Migration Strategy for Different Integration Scenarios

Your migration approach depends entirely on your current setup. Contact your third-party platform, vendor, or software provider (i.e., "shopping cart software" or "label creation software") directly for next steps before onboarding to USPS APIs. Ensure they are migrating from USPS Web Tools APIs to the new USPS APIs. They will need to direct you on what steps are required to successfully migrate to the new USPS APIs.

Direct API Integration Users: You're facing the most work. Complete endpoint restructuring, authentication overhaul, and data format conversion. Budget 3-6 months for proper testing and implementation.

TMS Platform Users: Check with your provider immediately. Platforms like Transporeon, Manhattan Active, or Blue Yonder should be handling the migration for you. The TMS is probably still integrating with FedEx's and UPS's APIs in some form or fashion, so it's still a pressing issue.

Multi-carrier Software Users: ShippyPro, Shippo, and similar platforms typically manage carrier API changes automatically. Verify your provider's migration timeline and any required updates to your integration.

3PL and Service Provider Dependencies: The same holds true for companies that are relying on 3PLs or other software providers to handle their parcel carrier interface. Don't assume your 3PL is handling this.

Testing and Validation Approach

To see the testing (a.k.a. TEM) and production endpoints, navigate to the right side of the page and This will display the TEM and PROD endpoints that will be used to generate your OAuth token in each environment. The test environment is a mirror of production for both your credentials and API functionality.

Test environment setup is mandatory. Unlike Web Tools where you could often test directly against production, the new APIs require proper staging validation. All Apps are initially granted access to the default "Public Access I" product which allows access to the following APIs (reference USPS Developer Portal API Catalog) with a quota of 60 calls per hour.

This quota limitation affects testing strategies. Plan your test scenarios carefully to stay within limits during development.

Common Implementation Challenges and Solutions

Learning from UPS and FedEx migrations reveals predictable issues. Despite the many announcements and guides that have been posted or sent out, many shipper companies still don't seem to have gotten the memo that complying with FedEx's and UPS's new API access requirements isn't going to be quick or easy. That's why it's important to let companies know that they can't wait until the last minute to begin upgrading and/or converting their technologies.

OAuth Token Expiration Issues: This OAuth access token needs to be regenerated after every 60 minutes and provided with each API transaction to authenticate and authorize your access to the FedEx resources. USPS uses 8-hour tokens, but you still need refresh logic.

Rate Limiting and Throttling: The new APIs have different rate limits than Web Tools. with a quota of 60 calls per hour for basic access. Enterprise access requires additional approvals.

Data Format Mapping: XML-to-JSON conversion isn't straightforward field mapping. USPS has restructured data hierarchies and field names. Expect 2-3 weeks of pure mapping work.

Integration Timeline Management: Integrations take money, time, and above all, skilled personnel. Many brokers and midsize carriers lack the internal IT teams and developers needed to create unique system bridges. As a result, the integration project is abandoned or just partially accomplished, completely delaying the benefits.

TMS Platform Considerations

Your TMS provider's migration readiness determines your timeline and complexity. Above all, shippers and carriers' want their TMS's to integrate smoothly with other technology systems. For shippers, that primarily means connecting to warehouse and yard management systems to avoid keeping data siloed in separate applications. Integrating technology platforms is especially important today, when businesses often have several sourcing locations and myriad modes of transport.

Questions to ask your TMS vendor:

  • When will USPS OAuth 2.0 support be available in production?
  • Will the migration require system updates or just configuration changes?
  • How will you handle the July 2025 disruption warnings?
  • What's your rollback plan if issues occur?

Modern platforms like Cargoson, nShift, or ShipStation typically handle these migrations transparently. Legacy TMS systems or custom-built platforms face more significant challenges.

As TMSes might communicate with other motor carrier TMS platforms, the ability to exchange data and other information between systems might be a challenge. Multi-TMS environments need coordinated migration approaches.

Fallback Strategies and Risk Mitigation

Prepare alternative carrier activation during migration. UPS Ground and FedEx Ground can handle most USPS volumes temporarily, though at higher costs. Budget 15-25% cost increases for backup carrier usage during transition periods.

Manual process backup plans are necessary. If your usage of label APIs has diminished to a low volume you might want to consider the Click-N-Ship application found at USPS.com® – Sign In. For European shippers with lower USPS volumes, manual label creation through Click-N-Ship can bridge service gaps.

Document your current USPS integration touchpoints. Many companies discover they're using USPS APIs in places they forgot about - address validation, delivery confirmation, pickup scheduling, or returns processing.

Post-Migration Optimization and Monitoring

webhooks push notifications, and improved performance become available after migration. Unlike Web Tools' polling-based approach, the new APIs support push notifications for tracking updates, delivery confirmations, and service exceptions.

Set up comprehensive monitoring. OAuth token expiration, API quotas, and webhook delivery failures need alerting. As much data as we store in a TMS, there is probably five times as much data in email inboxes. This disconnect leads to manual data transfer, or information that never makes it into the TMS.

Performance monitoring should track API response times, error rates, and cost per transaction. The new APIs often perform better than Web Tools, but initial implementations may have inefficiencies.

Cost comparison analysis matters. All Apps are initially granted access to the default "Public Access I" product which allows access to the following APIs with a quota of 60 calls per hour To request access to additional USPS APIs or to increase your API quota contact us. Higher quotas may require paid subscriptions.

Future-proofing considerations: USPS isn't the last carrier migration. Canada Post, Royal Mail, and other international carriers are modernizing their APIs. Build your integration architecture to handle OAuth 2.0 and webhook patterns as standard, not exceptions.

The January 2026 deadline is firm. There's always a chance, and both FedEx and UPS have adjusted their timelines, but I wouldn't want to bet on another schedule change. Start your migration planning now, not in December 2025.