Caching

The Ktor client provides the HttpCache plugin for caching previously fetched resources in memory or persistent storage.

Add dependencies

The HttpCache plugin is included in the ktor-client-core artifact and doesn't require any additional dependencies.

In-memory cache

To enable in-memory cache, install HttpCache in the client configuration block:

import io.ktor.client.*
import io.ktor.client.engine.cio.*
import io.ktor.client.plugins.cache.*
//...
val client = HttpClient(CIO) {
    install(HttpCache)
}

By default, the HttpCache plugin stores cached responses in memory.

For example, if you make two consecutive requests to a resource with a configured Cache-Control header, the client can serve the second response from the cache instead of requesting the resource again.

Persistent cache

You can store cached responses persistently by configuring a CacheStorage implementation.

Ktor provides the FileStorage() function, which stores cached responses in the file system. FileStorage() uses kotlinx-io and is available on all supported platforms.

Create a Path for the cache directory and pass it to the FileStorage() function. Then, configure the storage using the publicStorage() or privateStorage() functions:

        val client = HttpClient(CIO) {
            install(HttpCache) {
                publicStorage(FileStorage(Path("build/cache")))
            }
        }

Use the publicStorage() function for responses that can be stored in a shared cache.
Use the privateStorage() function for responses intended for a private cache.

25 August 2026