Debugging in distributed systems is notoriously challenging due to the interconnected nature of multiple API calls. API call tracing is essential for identifying bottlenecks, diagnosing errors, and optimizing system performance by capturing key metrics like response times, content type, and status codes. Distributed tracing tools, centralized logging and monitoring, use of correlation IDs, API gateway integration, real-time metrics with observability tools, standardizing API endpoints, monitoring multiple API calls, optimizing response times, validating requests, securing APIs, implementing rate limiting and retry policies are critical techniques for API call tracing in distributed systems. Advanced debugging techniques include leveraging a modular API development platform like Blackbird, which simulates production-like environments and enables proactively addressing the complexities of a distributed system from design stage onwards. By adopting these techniques, developers can simplify debugging in complex systems, identify bottlenecks and performance issues when multiple services work together, and ensure that debugging becomes less of a burden.