Marketplace Platform

The client had outgrown their original payment provider and needed to migrate to a new one. The problem was that payment logic was spread across nine services, each integrating directly with the provider's API in subtly different ways. Any attempt to swap the provider would have required coordinating changes across the entire codebase simultaneously.

We introduced an anti-corruption layer: a thin internal payment service that absorbed all provider-specific logic and exposed a clean, versioned internal API. Each of the nine services was re-pointed to the internal API one at a time, with the original provider still running behind it. No consumer needed to know anything had changed.

Once all services were routing through the abstraction layer, we ran the new provider in shadow mode for a week — receiving the same payment events and logging discrepancies without processing them. When the shadow logs showed full parity, we cut over in a single configuration change.

The migration completed in three weeks with no downtime. The client can now switch providers again in days rather than months.