Koen M. Vermeulen

Dutch software architect. Built multi-tenant carrier middleware for 1k+ shippers; advocates idempotency and good logs.

Amsterdam
Koen M. Vermeulen
Sandbox-to-Production Parity Testing for Carrier Integration: Detecting OAuth Cascade Failures and Rate Limiting Conflicts Before They Break Multi-Tenant Shipment Processing

Sandbox-to-Production Parity Testing for Carrier Integration: Detecting OAuth Cascade Failures and Rate Limiting Conflicts Before They Break Multi-Tenant Shipment Processing

USPS Web Tools shut down on January 25, 2026, and the Web Tools API platform marked just the beginning of a massive wave of carrier API retirements hitting enterprise integration teams. You've spent months perfecting your testing against stable sandbox environments. Your webhook endpoints pass every sandbox test,

By Koen M. Vermeulen
Distributed Rate Limiting Coordination for Multi-Tenant Carrier Integration: Redis Lua Patterns That Prevent Race Conditions Without Breaking Tenant Isolation During the 2026 Migration Crisis

Distributed Rate Limiting Coordination for Multi-Tenant Carrier Integration: Redis Lua Patterns That Prevent Race Conditions Without Breaking Tenant Isolation During the 2026 Migration Crisis

January 25, 2026 changed everything for carrier integration software. The Web Tools API platform shut down on Sunday, January 25, 2026, cutting off thousands of enterprise shipping integrations overnight. Web Services (SOAP) will be retired on June 1, 2026 for FedEx. Combined with the complexity of multi-tenant carrier integration

By Koen M. Vermeulen
Production-Grade Idempotency for Multi-Carrier Integration: Surviving OAuth Cascade Failures and Authentication Race Conditions Without Creating Duplicate Shipments

Production-Grade Idempotency for Multi-Carrier Integration: Surviving OAuth Cascade Failures and Authentication Race Conditions Without Creating Duplicate Shipments

The numbers tell a stark story. API downtime surged by 60% between Q1 2024 and Q1 2025, with average uptime dropping from 99.66% to 99.46%. For carrier integration teams, this means something worse than network timeouts: duplicate shipments and inventory mismanagement when retry logic fails. 73% of integration

By Koen M. Vermeulen
Zero-Downtime Traffic Routing Patterns for the 2026 Carrier API Migration Wave: Multi-Tenant Architectures That Survive SOAP-to-REST Transitions Without Breaking Shipment Processing

Zero-Downtime Traffic Routing Patterns for the 2026 Carrier API Migration Wave: Multi-Tenant Architectures That Survive SOAP-to-REST Transitions Without Breaking Shipment Processing

The USPS Web Tools API platform shut down on January 25, 2026, and FedEx SOAP endpoints will retire on June 1, 2026. This isn't just another platform upgrade. The Web Tools API platform shutdown marks the beginning of a massive wave of carrier API retirements hitting enterprise integration

By Koen M. Vermeulen