API

Making different systems work together through APIs creates persistent challenges including version management, authentication complexity, data format mismatches, and webhook reliability issues. These problems span multiple systems and are difficult for single vendors to solve comprehensively.

APIs are difficult to test compared to web applications because A/B testing different API design approaches is impractical. Developers cannot send out multiple API samples and expect users to program against all of them, making it challenging to validate API design decisions before widespread deployment.