You're debugging at 11 PM. The API returns 200 OK. Your app is broken anyway. A field got renamed upstream. No alert. No log. Just a confused user. Fixzi is the developer data workspace that catches this before your users do. Validate, fix, compare and monitor JSON, XML and API responses — in one place. 🚨 Standout feature: API Contract Monitoring — automatically checks your endpoints and alerts you when response structure changes.