Case study · Fintech · Go/TypeScript · 3 months

Fintech API — Coverage Up 32%

Contract and golden tests reduced incidents and supported faster iteration.

Fintech API — Coverage Up 32%

Context

  • Multiple downstream consumers with undocumented API behavior and breaking changes.
  • Long triage cycles with insufficient observability around error causes.

Actions

  • Added provider/consumer contract tests and golden tests for critical flows.
  • Implemented structured logging and tracing to shorten MTTD.
  • CI gated on contract validation; published API examples for partners.

Results

  • Statement generation incidents down 24%.
  • P99 latency improved 18% after removing synchronous IO in hot paths.
  • Developer onboarding time decreased with living API docs.
+32%
Test coverage
-24%
Incidents
-18%
P99 latency