Wiki
Reference articles for carrier API integration work — both general concepts (idempotency, retry strategies, SOAP envelopes) and precise vendor surfaces grouped by business unit, region, and protocol.
The wiki stays public and crawlable. Pro plans add deeper practice in lessons and arena without hiding these reference pages.
Carrier API surfaces
Browse all surfacesSpecific carrier APIs, organized so DHL Express, DHL eCommerce, and DHL Parcel DE are documented as separate surfaces rather than a single "DHL" page. Currently covers 13 surfaces across 7 vendors.
DHL Express, DHL eCommerce Solutions, DHL Post & Parcel Germany, UPS, FedEx (REST and SOAP), USPS, Royal Mail, La Poste Colissimo, and Australia Post.
Concept articles
A property of operations where performing them multiple times produces the same result as performing them once.
Patterns for automatically retrying failed carrier API requests without causing harm.
Understanding safe, idempotent, and unsafe HTTP methods in the context of carrier APIs.
A standard format for machine-readable error responses in HTTP APIs.
The XML wrapper structure for all SOAP messages.
The standard error response format in SOAP web services.
Web Services Description Language — the contract definition for SOAP services.
How XML namespaces prevent element name collisions in SOAP messages.
Unique identifiers that trace a request through distributed systems.
A resilience pattern that prevents cascading failures when a carrier API is down.
Foundational REST concepts as they apply to carrier integrations.
Strategies for classifying and handling carrier API errors.
How to cache, refresh, and invalidate carrier access tokens without creating an auth outage.
How to translate carrier throttling signals into queue-safe system behavior.
Verify webhook authenticity against the raw request body before you trust the event.
Protect webhook consumers against duplicate delivery and out-of-order carrier events.
Recover safely when the carrier completed part of the workflow and your system did not.
Use health checks and synthetic probes to tell carrier failures apart from your own regressions.
Route permanently failing carrier work into a queue built for inspection and recovery.
Validate SOAP payloads against the carrier contract before the request leaves your system.
Keep SOAP auth and transaction metadata in the header contract the carrier actually processes.
Use contract-aware tests to prove your generated SOAP client still matches the carrier's live expectations.
Track WSDL and schema changes as operational events so regenerated SOAP clients never surprise production.
Why a carrier integration that passes in sandbox can still fail on the first real shipment.
The type system for SOAP messages — defines the shape of request and response data.