Posted 10/03/2025

Response Caching vs. Output Caching in ASP.NET

Feature	Response Caching	Output Caching
Where the cache lives	On the client, proxy, CDN (external to server)	On the server (in memory, optionally distributed)
How it works	Adds HTTP headers (Cache-Control, Vary) so intermediaries can cache responses	Stores the generated response on the server and serves it directly without re-executing the endpoint
Best use cases	- Public APIs where proxies/CDNs can cache static or rarely-changing data - Browser caching of GET endpoints (e.g., product catalog, blog posts)	- Expensive server-side computations - Frequently requested responses where execution cost is high (e.g., report generation, user profile rendering)
Example	Response Caching in Minimap API	Output Caching in Minimap API
Pros	- Offloads server work to client/proxy - Reduces bandwidth	- Skips re-executing controller/endpoint - Works even if client disables caching
Cons	- Relies on client/proxy honoring headers - No server control once cached externally	- Increases server memory usage - Cache invalidation needed when data changes

When to use

• Use Response Caching when responses are static or public and can safely be cached by browsers/CDNs.
• Use Output Caching when responses are costly to generate and you want the server to short-circuit execution.
• Combine both if you want server + client/proxy caching.