dotnet/aspnetcore

ASP.NET Core is Microsoft's open-source web framework for building server-side web applications, APIs, and real-time services using C#. The problem it solves is providing a structured, high-performance foundation for building web services that would otherwise require developers to handle low-level concerns like HTTP routing, request parsing, authentication, middleware pipelines, and response serialization from scratch. ASP.NET Core packages all of that into a cohesive, productized framework. How it works: ASP.NET Core runs on top of the .NET runtime, which handles memory management, threading, and cross-platform execution. The framework is organized as a pipeline of middleware components, each incoming HTTP request passes through a chain of handlers (for logging, authentication, routing, compression, etc.) before reaching your application code. You define endpoints using either controller classes that map HTTP verbs to methods, or a newer "minimal API" style where routes are declared inline with short lambda functions. For web pages, Razor combines HTML templates with C# code to render dynamic HTML on the server. For real-time communication such as chat, ASP.NET Core includes SignalR, which maintains persistent WebSocket connections. You would use ASP.NET Core when building REST APIs consumed by a frontend or mobile app, server-rendered web applications in the .NET ecosystem, microservices in an enterprise environment, or any backend that benefits from the strong typing and tooling of C# and the performance of the .NET runtime. The tech stack is C# on the .NET runtime, running on Windows, macOS, and Linux. It integrates closely with Entity Framework Core for database access and can be deployed to the cloud, containers, or on-premises servers.