All 15 Caching questions
More in Caching
What is IMemoryCache, and when is it appropriate for an ASP.NET Core application? What is IDistributedCache, and how does it differ from IMemoryCache in a horizontally-scaled ASP.NET Core deployment? How does HybridCache (introduced in .NET 9) unify in-memory and distributed caching, and what problems does it solve? How do you configure Redis as the backing distributed cache for both IDistributedCache and Output Caching in the same application? What is the risk of caching sensitive or user-specific data with an incorrectly scoped cache key, and how do you prevent cross-user data leakage? How do you configure a cache entry's absolute versus sliding expiration, and when would you combine both? How does the [OutputCache] attribute's VaryByValue option let you cache based on custom, computed criteria beyond query strings or headers? What is response caching middleware, and how does it differ from application-level data caching? What is the 'cache stampede' (thundering herd) problem, and how would you mitigate it in an ASP.NET Core application? What are common cache invalidation strategies for ensuring cached data doesn't become stale, and why is invalidation considered a genuinely hard problem?
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ASP.NET Core › Caching

How does the newer Output Caching middleware (introduced in .NET 7) differ from Response Caching middleware?

Intermediate

Answer

Output Caching (UseOutputCache(), CacheOutput() policies) caches the response server-side (unlike Response Caching, which relies on client/proxy cache-control headers and doesn't actually store responses server-side by default), supports programmatic cache invalidation via tags, and offers a more flexible policy-based configuration model (varying by query string, header, or custom logic) -- generally the more powerful and recommended choice for server-side output caching going forward.
builder.Services.AddOutputCache(options => {
    options.AddPolicy("ProductsPolicy", policy => policy.Expire(TimeSpan.FromMinutes(5)).Tag("products"));
});
app.UseOutputCache();

app.MapGet("/products", () => GetProducts()).CacheOutput("ProductsPolicy");

// Invalidate all cached responses tagged 'products' when data changes:
await outputCacheStore.EvictByTagAsync("products", default);
Real-world example An e-commerce API uses Output Caching with tag-based invalidation, so updating any product immediately evicts all cached product-listing responses via EvictByTagAsync, rather than waiting for a fixed TTL to naturally expire potentially stale cached data.

Common follow-ups: Why is tag-based invalidation not available with Response Caching middleware?;Can Output Caching be configured to use a distributed store like Redis instead of in-memory?

ASP.NET Core Middleware & Request Pipeline;Configuration & Options Pattern
All 15 Caching questions