API and integration layer for a payments group

The client is a German payments group with a large and growing network of partner integrations built up over years. As the partner count climbed, the cost and fragility of connecting new partners was becoming a constraint on the business.

Their integration estate had grown organically rather than by design, and nobody had a complete map of how it all fit together.

Partner integrations had grown point-to-point and undocumented over years, so every new onboarding was a bespoke project. What should have been routine had become slow, expensive, and error-prone.

Any change risked a silent break in an integration nobody had fully mapped, and there was no observability to catch it until a partner complained. The estate was fragile in ways that were invisible until something failed.

As the partner network scaled, this integration sprawl was becoming a hard ceiling on growth. The group could not keep adding partners at the pace the business demanded without first fixing the foundation.

We built a governed API gateway with versioned contracts, so partners integrate against a stable, documented interface rather than internal implementation details. That decoupling is what makes each new integration routine rather than bespoke.

Self-service onboarding replaced the bespoke per-partner effort, and per-partner observability made every integration's health visible at a glance. Problems now surface as alerts rather than as partner complaints.

We migrated existing integrations behind the gateway incrementally, without a disruptive cutover, and versioned contracts meant future changes could ship without breaking live partners. The foundation was made solid without ever taking the network offline.