Gradion designs and builds integration layers for commerce platforms, logistics networks, payment systems, and operational infrastructure across DACH and Southeast Asia. The work is not glue code. It is the architecture that determines whether order data arrives once or twice, whether an ERP handoff fails silently at 3am, and whether the system can absorb a new fulfilment partner without a rewrite.

The engagements range from a single API design for an internal platform to full middleware architecture connecting a composable commerce stack across 30 markets. In each case, the contract design, versioning strategy, and failure handling are treated as first-class engineering concerns, not documentation tasks done after the fact.

What we build

REST and GraphQL API design:
Resource modelling, versioning policy, deprecation paths, and documentation that stays current with the implementation. OpenAPI specs, schema registries, and Postman collections maintained as part of the delivery, not handed over at the end. For GraphQL, schema boundaries that reflect domain logic rather than database tables, with query cost controls for production stability.

Middleware and integration architecture:
Message brokers, transformation pipelines, and retry logic with dead-letter queues for the failures that are not edge cases but certainties. Connectors against SAP, Shopware, Spryker, plentymarkets, and logistics networks across Europe and Southeast Asia, built against the real error modes of those systems under production load.

Event-driven systems:
Kafka-based streaming, domain event schemas versioned from the start, and consumer groups that scale independently. Applied where async processing genuinely reduces coupling and makes failure recovery explicit, not as a default architecture for every workflow. Order processing, inventory updates, and fulfilment triggers are the natural domain; we scope adoption to what the system actually needs.

Third-party and platform connectors:
Payment gateways, carrier APIs, ERP systems, and commerce platforms each have their own rate limits, quirks, and failure modes. We build connectors with circuit breakers, structured logging, and alerting on integration health. When a partner API degrades, the monitoring fires before the support queue fills.

API governance:
Version management policies, consumer registries, sunset timelines, and change notification processes that give teams lead time before a breaking change ships. For organisations building internal developer platforms, the same practices that make external APIs usable applied to internal service boundaries.

Proof in production

Switzerland’s leading mobile payment app, which processes 64% of all Swiss mobile payment transactions, needed a consistent integration layer across Shopware, WooCommerce, and Magento. The existing plugin architecture was fragmented: different implementations for each platform, inconsistent merchant experience, high maintenance overhead. Gradion built an SDK-based framework with a reusable core, unifying the integration surface across all three platforms and reducing merchant onboarding friction across the Swiss e-commerce market.

HomeToGo operates a travel platform aggregating real-time inventory from over 100 partner APIs across 15 million+ listings. Gradion built and maintains the integration layer that keeps that inventory current across markets and time zones, with the fault isolation and retry architecture that makes aggregation at that scale operationally stable.

CTA

Describe the systems you need to connect. We will scope the integration and flag the failure modes before they reach production.