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+---
+title: Configure the HTTP cache
+linkTitle: HTTP cache
+description: Configure the HTTP cache.
+categories: []
+keywords: []
+---
+
+> [!note]
+> This configuration is only relevant when using the [`resources.GetRemote`] function.
+
+## Layered caching
+
+Hugo employs a layered caching system.
+
+```goat {.w-40}
+ .-----------.
+|  dynacache  |
+ '-----+-----'
+       |
+       v
+ .----------.
+| HTTP cache |
+ '-----+----'
+       |
+       v
+ .----------.
+| file cache |
+ '-----+----'
+```
+
+Dynacache
+: An in-memory cache employing a Least Recently Used (LRU) eviction policy. Entries are removed from the cache when changes occur, when they match [cache-busting] patterns, or under low-memory conditions.
+
+HTTP Cache
+: An HTTP cache for remote resources as specified in [RFC 9111]. Optimal performance is achieved when resources include appropriate HTTP cache headers. The HTTP cache utilizes the file cache for storage and retrieval of cached resources.
+
+File cache
+: See [configure file caches].
+
+The HTTP cache involves two key aspects: determining which content to cache (the caching process itself) and defining the frequency with which to check for updates (the polling strategy).
+
+## HTTP caching
+
+The HTTP cache behavior is defined for a configured set of resources. Stale resources will be refreshed from the file cache, even if their configured Time-To-Live (TTL) has not expired. If HTTP caching is disabled for a resource, Hugo will bypass the cache and access the file directly.
+
+The default configuration disables everything:
+
+{{< code-toggle file=hugo >}}
+[HTTPCache.cache.for]
+excludes = ['**']
+includes = []
+{{< /code-toggle >}}
+
+cache.for.excludes
+: (`string`) A list of [glob](g) patterns to exclude from caching.
+
+cache.for.includes
+: (`string`) A list of [glob](g) patterns to cache.
+
+## HTTP polling
+
+Polling is used in watch mode (e.g., `hugo server`) to detect changes in remote resources. Polling can be enabled even if HTTP caching is disabled. Detected changes trigger a rebuild of pages using the affected resource. Polling can be disabled for specific resources, typically those known to be static.
+
+The default configuration disables everything:
+
+{{< code-toggle file=hugo >}}
+[[HTTPCache.polls]]
+disable = true
+high = '0s'
+low = '0s'
+[HTTPCache.polls.for]
+includes = ['**']
+excludes = []
+{{< /code-toggle >}}
+
+polls
+: A slice of polling configurations.
+
+polls.disable
+: (`bool`) Whether to disable polling for this configuration.
+
+polls.low
+: (`string`) The minimum polling interval expressed as a [duration](g). This is used after a recent change and gradually increases towards `polls.high`.
+
+polls.high
+: (`string`) The maximum polling interval expressed as a [duration](g). This is used when the resource is considered stable.
+
+polls.for.excludes
+: (`string`) A list of [glob](g) patterns to exclude from polling for this configuration.
+
+polls.for.includes
+: (`string`) A list of [glob](g) patterns to include in polling for this configuration.
+
+## Behavior
+
+Polling and HTTP caching interact as follows:
+
+- With polling enabled, rebuilds are triggered only by actual changes, detected via `eTag` changes (Hugo generates an MD5 hash if the server doesn't provide one).
+- If polling is enabled but HTTP caching is disabled, the remote is checked for changes only after the file cache's TTL expires (e.g., a `maxAge` of `10h` with a `1s` polling interval is inefficient).
+- If both polling and HTTP caching are enabled, changes are checked for even before the file cache's TTL expires. Cached `eTag` and `last-modified` values are sent in `if-none-match` and `if-modified-since` headers, respectively, and a cached response is returned on HTTP [304].
+
+[`resources.GetRemote`]: /functions/resources/getremote/
+[304]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/304
+[cache-busting]: /configuration/build/#cache-busters
+[configure file caches]: /configuration/caches/
+[RFC 9111]: https://datatracker.ietf.org/doc/html/rfc9111