The challenge
Thirty interfaces published on an API management platform, near-zero internal adoption, and no clear authority over interface contracts between the group's entities.
The outcome
Design guidelines adopted by all six entities, a review process wired into the CI chain, and a move from three to twenty-two genuinely consumed interfaces in twelve months.
The context
The group had invested in an API management platform two years earlier. Entities published their interfaces with no shared reference. Every consuming team had to understand a different data model, unevenly documented, with no guarantee of stability.
Our approach
We started by measuring: which interfaces were consumed, by whom, and how often. The findings became the basis for discussion with the technical leadership of all six entities.
Three workstreams followed:
- Design guidelines built with representatives from each entity rather than imposed by central architecture. Naming conventions, versioning, error formats, pagination.
- A tooled review process — guideline compliance is checked automatically in the integration chain, and human review focuses on the domain model.
- Explicit contract authority — every interface has a named owner, the only person able to accept a breaking change.
The outcome
Within twelve months, the number of genuinely consumed interfaces went from three to twenty-two. The total number of published interfaces actually fell: eleven were retired for want of a consumer.