HTTP Cache Control Directives (Types)

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ICSM Computer · Answer

HTTP Cache Control Directives (Types)
Directive
Description
public
Can be cached by any cache (browser, CDN, proxy). Safe for shared caching.
private
Can be cached only by the browser. Not cached by shared caches like proxies.
no-cache
Cached copy must be revalidated with the server before being used.
no-store
Do not cache at all — not even in memory. Best for sensitive data (e.g., login).
max-age=n
Specifies how long (in seconds) the response is considered fresh.
s-maxage=n
Like max-age, but specific to shared caches (e.g., CDNs).
must-revalidate
The cache must check with the server before using expired content.
proxy-revalidate
Like must-revalidate, but for shared caches.
immutable
Indicates the response won’t change, so no need to revalidate.
stale-while-revalidate
Allows serving stale content while revalidating in the background.
Examples
1. Public
Cache-Control: public, max-age=86400
Can be stored by browser and intermediate caches (CDNs, proxies).Good for static files like images, CSS, JS.
2. Private
Cache-Control: private, max-age=600
Only the end user's browser can cache this.Useful for personalized content (e.g., user dashboards).
3. No-Cache
Cache-Control: no-cache
Cached, but must check with server before using.Safer when data might change frequently.
4. No-Store
Cache-Control: no-store
No caching allowed. Not stored in memory, disk, or anywhere.Used for sensitive data (e.g., banking, login pages).
Summary Table
Directive
Can Cache?
Who Can Cache?
Needs Validation?
Use Case
public
Yes
Anyone (browser, CDN)
if fresh
Static resources
private
Yes
Browser only
if fresh
User-specific pages
no-cache
Yes
Browser or CDN
always
Dynamic but not sensitive
no-store
NO
Nobody
always
Passwords, banking info
max-age=3600
Yes
Depends on public/private
for set duration
Control how long it's fresh

Directive	Description
`public`	Can be cached by any cache (browser, CDN, proxy). Safe for shared caching.
`private`	Can be cached only by the browser. Not cached by shared caches like proxies.
`no-cache`	Cached copy must be revalidated with the server before being used.
`no-store`	Do not cache at all — not even in memory. Best for sensitive data (e.g., login).
`max-age=n`	Specifies how long (in seconds) the response is considered fresh.
`s-maxage=n`	Like `max-age`, but specific to shared caches (e.g., CDNs).
`must-revalidate`	The cache must check with the server before using expired content.
`proxy-revalidate`	Like `must-revalidate`, but for shared caches.
`immutable`	Indicates the response won’t change, so no need to revalidate.
`stale-while-revalidate`	Allows serving stale content while revalidating in the background.

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HTTP Cache Control Directives (Types)

ICSM Computer

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1 Answers

HTTP Cache Control Directives (Types)

Examples

1. Public

2. Private

3. No-Cache

4. No-Store

Summary Table

Liked By

Directive	Can Cache?	Who Can Cache?	Needs Validation?	Use Case
`public`	Yes	Anyone (browser, CDN)	if fresh	Static resources
`private`	Yes	Browser only	if fresh	User-specific pages
`no-cache`	Yes	Browser or CDN	always	Dynamic but not sensitive
`no-store`	NO	Nobody	always	Passwords, banking info
`max-age=3600`	Yes	Depends on public/private	for set duration	Control how long it's fresh