APIs are the backbone of modern applications, but securing them requires more than just enabling authentication. In this session, we’ll dive into key security principles for API protection, covering authentication, authorization, and code validation strategies. We’ll explore how to leverage C# capabilities, such as middleware, attributes, and analyzers, to enforce security best practices at compile-time and runtime. Additionally, we’ll discuss common vulnerabilities and how to mitigate them, ensuring your APIs remain resilient against evolving threats. Whether you’re building internal services or public-facing APIs, this talk will provide actionable insights to enhance your security posture.