diff --git a/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClient.kt b/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClient.kt
index 634e8f0..3d478c3 100644
--- a/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClient.kt
+++ b/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClient.kt
@@ -18,4 +18,17 @@ interface AnthropicClient {
     fun models(): ModelService
 
     fun beta(): BetaService
+
+    /**
+     * Closes this client, relinquishing any underlying resources.
+     *
+     * This is purposefully not inherited from [AutoCloseable] because the client is long-lived and
+     * usually should not be synchronously closed via try-with-resources.
+     *
+     * It's also usually not necessary to call this method at all. the default HTTP client
+     * automatically releases threads and connections if they remain idle, but if you are writing an
+     * application that needs to aggressively release unused resources, then you may call this
+     * method.
+     */
+    fun close()
 }
diff --git a/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientAsync.kt b/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientAsync.kt
index bc9af30..c5dc2dc 100644
--- a/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientAsync.kt
+++ b/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientAsync.kt
@@ -18,4 +18,17 @@ interface AnthropicClientAsync {
     fun models(): ModelServiceAsync
 
     fun beta(): BetaServiceAsync
+
+    /**
+     * Closes this client, relinquishing any underlying resources.
+     *
+     * This is purposefully not inherited from [AutoCloseable] because the client is long-lived and
+     * usually should not be synchronously closed via try-with-resources.
+     *
+     * It's also usually not necessary to call this method at all. the default HTTP client
+     * automatically releases threads and connections if they remain idle, but if you are writing an
+     * application that needs to aggressively release unused resources, then you may call this
+     * method.
+     */
+    fun close()
 }
diff --git a/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientAsyncImpl.kt b/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientAsyncImpl.kt
index 99adf09..11645b5 100644
--- a/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientAsyncImpl.kt
+++ b/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientAsyncImpl.kt
@@ -52,4 +52,6 @@ constructor(
     override fun models(): ModelServiceAsync = models
 
     override fun beta(): BetaServiceAsync = beta
+
+    override fun close() = clientOptions.httpClient.close()
 }
diff --git a/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientImpl.kt b/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientImpl.kt
index 7c44418..bbd28db 100644
--- a/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientImpl.kt
+++ b/anthropic-java-core/src/main/kotlin/com/anthropic/client/AnthropicClientImpl.kt
@@ -48,4 +48,6 @@ constructor(
     override fun models(): ModelService = models
 
     override fun beta(): BetaService = beta
+
+    override fun close() = clientOptions.httpClient.close()
 }