C.A.R.D.S.: A heuristic for reliable API testing

APIs are the backbone of modern systems, yet ensuring their reliability in complex environments can be daunting. During my talk, I’ll address the challenge of comprehensive API testing, where gaps in validation often lead to failures in production, missed edge cases, or degraded user experiences. To tackle this, I developed C.A.R.D.S., a structured approach that breaks API testing into five essential dimensions: Connections, Attributes, Rules, Data, and Sequences. By focusing on external integrations, validating response structures, enforcing business rules, scrutinizing data handling, and analyzing call sequences, C.A.R.D.S. enables testers to uncover vulnerabilities and ensure APIs handle real-world scenarios gracefully. This heuristic has been applied to diverse projects, uncovering critical issues like concurrency bugs and data inconsistencies that traditional methods often overlook. Delegates will leave with a practical framework to enhance their API testing strategy, actionable tips to identify edge cases, and insights on improving system resilience. Whether they’re seasoned testers or new to API testing, attendees will gain tools to deliver more reliable and user-focused APIs.