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ASP.NET Core › Caching

What is response caching middleware, and how does it differ from application-level data caching?

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Answer

Response caching (via UseResponseCaching() and [ResponseCache] attributes) caches entire HTTP responses at the HTTP layer based on cache-control headers, serving cached output directly without re-invoking the controller action at all -- distinct from application-level data caching (IMemoryCache/IDistributedCache), which caches specific pieces of data used within business logic, potentially still requiring the full request pipeline to execute.
builder.Services.AddResponseCaching();
app.UseResponseCaching();

[ResponseCache(Duration = 60, VaryByQueryKeys = new[] { "category" })]
[HttpGet]
public IActionResult GetProducts(string category) => Ok(_products.Where(p => p.Category == category));
Real-world example A public product catalog API caches entire GET /products?category=electronics responses for 60 seconds using response caching middleware, avoiding the full controller execution (including any data-layer caching logic) entirely for repeated identical requests within that window.

Common follow-ups: How does VaryByQueryKeys affect what counts as a 'unique' cached response?;How does response caching interact with a CDN sitting in front of the API?

ASP.NET Core Middleware & Request Pipeline;Content Negotiation & Output Formatters
All 15 Caching questions