Dotnet Core - Response Caching vs Output Caching

 ⚖️ Response Caching vs Output Caching in ASP.NET Core

Aspect	Response Caching	Output Caching
Purpose	Instructs clients (like browsers) and proxies to cache responses	Caches the actual server-generated response in memory (on the server)
Caching Location	Client-side (browser, CDN, proxy)	Server-side (in ASP.NET Core memory or distributed cache)
Implementation	Uses HTTP Cache-Control headers and middleware	Uses the new OutputCache Middleware (ASP.NET Core 7+)
How it Works	Adds headers like Cache-Control, Vary, etc. → tells browser/CDN when to reuse responses	Middleware saves response output → reuses for identical requests without re-running controller/action
Scope	Works outside server (helps client cache responses)	Works inside server (bypasses controller execution)
Configuration Example	csharp\n[ResponseCache(Duration = 60, Location = ResponseCacheLocation.Client)]\n	csharp\napp.UseOutputCache();\n[OutputCache(Duration = 60)]\n
Dependencies	Relies on clients or CDNs honoring headers	Fully managed by ASP.NET Core runtime
Use Case	Static or semi-static responses (e.g., images, GET APIs)	Heavy computation APIs, views, or controller actions with repeated requests
Introduced in	.NET Core 1.0+	.NET 7.0+
Invalidation	Controlled by headers (no-cache, max-age)	Controlled programmatically (OutputCacheStore can evict or tag invalidations)

🧩 Example Scenarios

• ✅ Response Caching

  • Browser caches a product list API for 60 seconds.

  • CDN serves cached version — no new request hits your API.

  • Great for read-heavy GET endpoints.

• ✅ Output Caching

  • Server caches rendered HTML for /home/index or JSON for /api/dashboard.

  • Subsequent requests return cached result from memory — controller not even called.

  • Great for high CPU or DB-intensive endpoints.

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🔧 Combined Use

You can combine both:

• Server caches the response using Output Cache.

• Sends ResponseCache headers to help client/CDN reuse it.

This provides multi-level caching — server + client.