For years, the biggest criticism of ASP.NET Core Minimal APIs was the lack of native request validation. Developers either pulled in third-party libraries like FluentValidation or wrote repetitive manual checks inside every endpoint handler. With .NET 10, that gap is officially closed.
How Built-In Validation Works
The new validation system integrates directly into the Minimal API pipeline. During startup, you call builder.Services.AddValidation(), and the framework registers a validation filter that automatically inspects your Data Annotation attributes — [Required], [MaxLength], [Range], and all the rest.
If validation fails, the request never reaches your handler. The pipeline short-circuits and returns a 400 response with a structured Problem Details body. There are no manual if-checks and no try-catch wrappers needed.
Broader Scope Than Expected
What makes this particularly noteworthy is the scope of coverage. Validation now applies to query strings, headers, and route parameters — not just the request body. This is a broader reach than most developers anticipate, and it eliminates an entire class of input-handling bugs that previously required custom middleware or filters.
Compile-Time Safety Without Reflection
The implementation uses source-generated interceptors, which means you get compile-time safety without the reflection overhead that typically comes with runtime validation. This is a meaningful performance advantage for high-throughput services where every microsecond of request processing matters.
Takeaway
If you have been holding off on adopting Minimal APIs for production services because of the validation story, that barrier no longer exists. The combination of native Data Annotation support, automatic pipeline integration, and source-generated performance makes .NET 10 Minimal APIs a genuinely production-ready option for teams building modern web services.
