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ArchitectureLogistics / BackendBackendCloud
Multi-Carrier Shipping Integration
Extensible TypeScript shipping-rate service designed to integrate UPS, FedEx, DHL, and future carriers without coupling third-party APIs to core business logic.
github · source
Architecture/ the problem
Shipping rate APIs differ wildly by carrier. Embedding UPS-specific payloads in business logic makes every new carrier a rewrite, and OAuth token handling becomes fragile under load.
/ approach
The engineering team implemented an extensible carrier-adapter architecture with OAuth handling and testable domain boundaries.
/ what we built
- Strategy-pattern ICarrier interface isolating ShippingService from carrier quirks
- Mapper buffer zone so domain models stay free of carrier field names
- UPS adapter with OAuth 2.0 client-credentials, token caching, proactive refresh, and 401 retry
- Zod environment validation, Axios client, Jest + Nock integration tests, structured errors
/ the outcome
A carrier-agnostic shipping-rate module with a working UPS path and a clear extension point for future FedEx and DHL adapters, without implying those adapters are already complete.
/ next case study
Home Detection Lab