GLS UniBox to REST API migration
Migrating From GLS UniBox To The REST API
A step-by-step guide to migrating from GLS UniBox to the GLS ShipIT REST API, covering credentials, createParcels, idempotency and ConfirmLabel.
Koen M. Vermeulen
Dutch software architect. Built multi-tenant carrier middleware for 1k+ shippers; advocates idempotency and good logs.
batch shipment API limits
Batch Shipment Limits Across 9 Carrier APIs
Batch and bulk-request limits for FedEx, UPS, DHL, USPS, Shippo, EasyPost, Sendcloud and more — sourced from current docs, dated October 2026.
dead letter queue
Dead Letter Queue vs Retry Queue: The Real Difference
Dead letter queue explained for carrier integration: how it differs from a retry queue, with a worked webhook example and FAQ.
PostNL API migration
Migrating to PostNL Shipment API v4, Step by Step
How to move a production PostNL integration to Shipment API v4: field mapping, barcode-to-reference tracking, key rotation, and rollback steps.
carrier integration software uptime
Carrier Integration Software Uptime: 12 SLAs Compared
Published uptime SLAs, marketing claims, and measured data for 12 carrier integration and shipping API platforms, as of September 2026.
transactional outbox pattern
The Transactional Outbox Pattern, Explained
How the transactional outbox pattern stops shipment records and carrier webhooks drifting out of sync, with a worked booking example.
UPS API OAuth 2.0 migration
Migrating UPS API from XML to OAuth 2.0 REST
A step-by-step guide to migrating multi-tenant UPS integrations from XML/Access Key to OAuth 2.0 REST, with token-caching to avoid rate limits.
multi-carrier shipping software pricing
Multi-Carrier Shipping Software Pricing: 9 Vendors
Per-label fees, subscription tiers, and free-plan limits across nine multi-carrier shipping platforms, sourced from vendor pricing pages, September 2026.
rate shopping
Rate Shopping, Explained
What rate shopping means in carrier integration software, how fan-out vs cached rate engines differ, and how to budget timeouts across carriers.
SSCC label generation
Generating SSCC-18 Labels in a Multi-Tenant Platform
Learn to generate GS1-128 SSCC-18 pallet labels in a multi-tenant carrier platform: AI structure, Mod-10 checks, ZPL output, and tenant-safe serials.
carrier count comparison
Carrier Count Claims: What 9 Vendors Publish
We checked carrier-count claims on 9 multi-carrier platforms' own pages. See the table, the contradictions, and what to verify before you build.
transportation spend management
Transportation Spend Management, Explained
What transportation spend management is, how it differs from freight audit and a TMS, and the data pipeline that makes it trustworthy.