CORS middleware
CORS middleware is an HTTP pipeline component that evaluates cross-origin requests and applies configured policies, including handling preflight requests and response headers.
Building Web APIs with ASP.NET Core
CORS middleware is an HTTP pipeline component that applies cross-origin request policies to web API requests and responses.
- How it is used
- Applies a selected CORS policy across controllers and Minimal API endpoints in a board-game API.
- How deep it goes
- Shows policy registration and middleware placement, then contrasts global application with endpoint-level alternatives.
- Examples
- Uses `Program.cs` configurations for a default policy, an `AnyOrigin` policy, and an `AllowedOrigins` setting.
- What you can do after
- Operate/configure it by placing `app.UseCors()` before authorization and choosing between default and named policies.
Read how Building Web APIs with ASP.NET Core explains CORS middleware →
ASP.NET Core in Action, 3e
CorsMiddleware is the ASP.NET Core middleware component that evaluates endpoint CORS metadata and applies the corresponding CORS policy.
- How it is used
- Controls browser access to APIs hosted on a different origin, globally or for selected ASP.NET Core endpoints.
- How deep it goes
- Explains registration, policy configuration, pipeline ordering, and endpoint selection, but stops short of internal middleware implementation.
- Examples
- Uses a shopping API, an allowed shopping origin, named policies, global middleware, and endpoint-specific RequireCors and EnableCors examples.
- What you can do after
- Operate/configure ASP.NET Core CORS with named policies, global defaults, or endpoint-specific rules.
Read how ASP.NET Core in Action, 3e explains CORS middleware →
Related concepts
- UseCorsused by · UseCors is an ASP.NET Core application-builder method that adds CORS middleware and optionally selects a default policy.
- cachingconfigures · Caching is the practice of storing reusable data or computation results so later access can avoid repeating retrieval or computation.
- CORSuses · Cross-Origin Resource Sharing (CORS) is a web standard that uses HTTP headers to let servers specify which origins may access their resources through browsers.
- middlewarekind of · Middleware is an intermediate software component or layer that processes or mediates requests, messages, or operations between other components, often adding behavior or controlling their flow.
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