diff --git a/armeria-backend/cats-ce2/src/main/scala/sttp/client4/armeria/cats/ArmeriaCatsBackend.scala b/armeria-backend/cats-ce2/src/main/scala/sttp/client4/armeria/cats/ArmeriaCatsBackend.scala
index fa3b6c7e92..087f2722c8 100644
--- a/armeria-backend/cats-ce2/src/main/scala/sttp/client4/armeria/cats/ArmeriaCatsBackend.scala
+++ b/armeria-backend/cats-ce2/src/main/scala/sttp/client4/armeria/cats/ArmeriaCatsBackend.scala
@@ -57,11 +57,11 @@ object ArmeriaCatsBackend {
   def resourceUsingClient[F[_]: Concurrent](client: WebClient): Resource[F, Backend[F]] =
     Resource.make(Sync[F].delay(apply(client, closeFactory = true)))(_.close())
 
-  def usingDefaultClient[F[_]: Concurrent](): Backend[F] =
-    apply(newClient(), closeFactory = false)
+  def usingDefaultClient[F[_]: Concurrent](closeFactory: Boolean = false): Backend[F] =
+    apply(newClient(), closeFactory = closeFactory)
 
-  def usingClient[F[_]: Concurrent](client: WebClient): Backend[F] =
-    apply(client, closeFactory = false)
+  def usingClient[F[_]: Concurrent](client: WebClient, closeFactory: Boolean = false): Backend[F] =
+    apply(client, closeFactory = closeFactory)
 
   private def apply[F[_]: Concurrent](
       client: WebClient,
diff --git a/armeria-backend/cats/src/main/scala/sttp/client4/armeria/cats/ArmeriaCatsBackend.scala b/armeria-backend/cats/src/main/scala/sttp/client4/armeria/cats/ArmeriaCatsBackend.scala
index e6926edfd1..1e1bfd3c7f 100644
--- a/armeria-backend/cats/src/main/scala/sttp/client4/armeria/cats/ArmeriaCatsBackend.scala
+++ b/armeria-backend/cats/src/main/scala/sttp/client4/armeria/cats/ArmeriaCatsBackend.scala
@@ -56,11 +56,11 @@ object ArmeriaCatsBackend {
   def resourceUsingClient[F[_]: Async](client: WebClient): Resource[F, Backend[F]] =
     Resource.make(Sync[F].delay(apply(client, closeFactory = true)))(_.close())
 
-  def usingDefaultClient[F[_]: Async](): Backend[F] =
-    apply(newClient(), closeFactory = false)
+  def usingDefaultClient[F[_]: Async](closeFactory: Boolean = false): Backend[F] =
+    apply(newClient(), closeFactory = closeFactory)
 
-  def usingClient[F[_]: Async](client: WebClient): Backend[F] =
-    apply(client, closeFactory = false)
+  def usingClient[F[_]: Async](client: WebClient, closeFactory: Boolean = false): Backend[F] =
+    apply(client, closeFactory = closeFactory)
 
   private def apply[F[_]: Async](
       client: WebClient,
diff --git a/armeria-backend/fs2-ce2/src/main/scala/sttp/client4/armeria/fs2/ArmeriaFs2Backend.scala b/armeria-backend/fs2-ce2/src/main/scala/sttp/client4/armeria/fs2/ArmeriaFs2Backend.scala
index 2d3b665bec..67657b0c28 100644
--- a/armeria-backend/fs2-ce2/src/main/scala/sttp/client4/armeria/fs2/ArmeriaFs2Backend.scala
+++ b/armeria-backend/fs2-ce2/src/main/scala/sttp/client4/armeria/fs2/ArmeriaFs2Backend.scala
@@ -63,11 +63,11 @@ object ArmeriaFs2Backend {
   def resourceUsingClient[F[_]: ConcurrentEffect](client: WebClient): Resource[F, StreamBackend[F, Fs2Streams[F]]] =
     Resource.make(Sync[F].delay(apply(client, closeFactory = true)))(_.close())
 
-  def usingClient[F[_]: ConcurrentEffect](client: WebClient): StreamBackend[F, Fs2Streams[F]] =
-    apply(client, closeFactory = false)
+  def usingClient[F[_]: ConcurrentEffect](client: WebClient, closeFactory: Boolean = false): StreamBackend[F, Fs2Streams[F]] =
+    apply(client, closeFactory = closeFactory)
 
-  def usingDefaultClient[F[_]: ConcurrentEffect](): StreamBackend[F, Fs2Streams[F]] =
-    apply(newClient(), closeFactory = false)
+  def usingDefaultClient[F[_]: ConcurrentEffect](closeFactory: Boolean = false): StreamBackend[F, Fs2Streams[F]] =
+    apply(newClient(), closeFactory = closeFactory)
 
   private def apply[F[_]: ConcurrentEffect](
       client: WebClient,
diff --git a/armeria-backend/fs2/src/main/scala/sttp/client4/armeria/fs2/ArmeriaFs2Backend.scala b/armeria-backend/fs2/src/main/scala/sttp/client4/armeria/fs2/ArmeriaFs2Backend.scala
index 48525db9fb..bbef468132 100644
--- a/armeria-backend/fs2/src/main/scala/sttp/client4/armeria/fs2/ArmeriaFs2Backend.scala
+++ b/armeria-backend/fs2/src/main/scala/sttp/client4/armeria/fs2/ArmeriaFs2Backend.scala
@@ -80,11 +80,11 @@ object ArmeriaFs2Backend {
       .parallel[F]
       .flatMap(dispatcher => Resource.make(Sync[F].delay(apply(client, closeFactory = true, dispatcher)))(_.close()))
 
-  def usingClient[F[_]: Async](client: WebClient, dispatcher: Dispatcher[F]): StreamBackend[F, Fs2Streams[F]] =
-    apply(client, closeFactory = false, dispatcher)
+  def usingClient[F[_]: Async](client: WebClient, dispatcher: Dispatcher[F], closeFactory: Boolean = false): StreamBackend[F, Fs2Streams[F]] =
+    apply(client, closeFactory = closeFactory, dispatcher)
 
-  def usingDefaultClient[F[_]: Async](dispatcher: Dispatcher[F]): StreamBackend[F, Fs2Streams[F]] =
-    apply(newClient(), closeFactory = false, dispatcher)
+  def usingDefaultClient[F[_]: Async](dispatcher: Dispatcher[F], closeFactory: Boolean = false): StreamBackend[F, Fs2Streams[F]] =
+    apply(newClient(), closeFactory = closeFactory, dispatcher)
 
   private def apply[F[_]: Async](
       client: WebClient,
diff --git a/armeria-backend/monix/src/main/scala/sttp/client4/armeria/monix/ArmeriaMonixBackend.scala b/armeria-backend/monix/src/main/scala/sttp/client4/armeria/monix/ArmeriaMonixBackend.scala
index 3a4c90cb7b..3bd5f12515 100644
--- a/armeria-backend/monix/src/main/scala/sttp/client4/armeria/monix/ArmeriaMonixBackend.scala
+++ b/armeria-backend/monix/src/main/scala/sttp/client4/armeria/monix/ArmeriaMonixBackend.scala
@@ -55,16 +55,16 @@ object ArmeriaMonixBackend {
     apply(newClient(options), closeFactory = true)
 
   /** @param scheduler The scheduler used for streaming request bodies. Defaults to the global scheduler. */
-  def usingClient(client: WebClient)(implicit
+  def usingClient(client: WebClient, closeFactory: Boolean = false)(implicit
       scheduler: Scheduler = Scheduler.global
   ): StreamBackend[Task, MonixStreams] =
-    apply(client, closeFactory = false)
+    apply(client, closeFactory = closeFactory)
 
   /** @param scheduler The scheduler used for streaming request bodies. Defaults to the global scheduler. */
-  def usingDefaultClient()(implicit
+  def usingDefaultClient(closeFactory: Boolean = false)(implicit
       scheduler: Scheduler = Scheduler.global
   ): StreamBackend[Task, MonixStreams] =
-    apply(newClient(), closeFactory = false)
+    apply(newClient(), closeFactory = closeFactory)
 
   private def apply(client: WebClient, closeFactory: Boolean)(implicit
       scheduler: Scheduler
diff --git a/armeria-backend/scalaz/src/main/scala/sttp/client4/armeria/scalaz/ArmeriaScalazBackend.scala b/armeria-backend/scalaz/src/main/scala/sttp/client4/armeria/scalaz/ArmeriaScalazBackend.scala
index a312cbb5fa..26f745e8ee 100644
--- a/armeria-backend/scalaz/src/main/scala/sttp/client4/armeria/scalaz/ArmeriaScalazBackend.scala
+++ b/armeria-backend/scalaz/src/main/scala/sttp/client4/armeria/scalaz/ArmeriaScalazBackend.scala
@@ -47,9 +47,9 @@ object ArmeriaScalazBackend {
   def apply(options: BackendOptions = BackendOptions.Default): Backend[Task] =
     apply(newClient(options), closeFactory = true)
 
-  def usingClient(client: WebClient): Backend[Task] = apply(client, closeFactory = false)
+  def usingClient(client: WebClient, closeFactory: Boolean = false): Backend[Task] = apply(client, closeFactory = closeFactory)
 
-  def usingDefaultClient(): Backend[Task] = apply(newClient(), closeFactory = false)
+  def usingDefaultClient(closeFactory: Boolean = false): Backend[Task] = apply(newClient(), closeFactory = closeFactory)
 
   private def apply(
       client: WebClient,
diff --git a/armeria-backend/src/main/scala/sttp/client4/armeria/future/ArmeriaFutureBackend.scala b/armeria-backend/src/main/scala/sttp/client4/armeria/future/ArmeriaFutureBackend.scala
index b13d9f73da..3eef6791c6 100644
--- a/armeria-backend/src/main/scala/sttp/client4/armeria/future/ArmeriaFutureBackend.scala
+++ b/armeria-backend/src/main/scala/sttp/client4/armeria/future/ArmeriaFutureBackend.scala
@@ -48,11 +48,11 @@ object ArmeriaFutureBackend {
   def apply(options: BackendOptions = BackendOptions.Default): Backend[Future] =
     apply(newClient(options), closeFactory = true)
 
-  def usingClient(client: WebClient): Backend[Future] =
-    apply(client, closeFactory = false)
+  def usingClient(client: WebClient, closeFactory: Boolean = false): Backend[Future] =
+    apply(client, closeFactory = closeFactory)
 
-  def usingDefaultClient(): Backend[Future] =
-    apply(newClient(), closeFactory = false)
+  def usingDefaultClient(closeFactory: Boolean = false): Backend[Future] =
+    apply(newClient(), closeFactory = closeFactory)
 
   private def apply(client: WebClient, closeFactory: Boolean): Backend[Future] =
     FollowRedirectsBackend(new ArmeriaFutureBackend(client, closeFactory))
diff --git a/armeria-backend/zio/src/main/scala/sttp/client4/armeria/zio/ArmeriaZioBackend.scala b/armeria-backend/zio/src/main/scala/sttp/client4/armeria/zio/ArmeriaZioBackend.scala
index 5d7e124cab..5ae20812b2 100644
--- a/armeria-backend/zio/src/main/scala/sttp/client4/armeria/zio/ArmeriaZioBackend.scala
+++ b/armeria-backend/zio/src/main/scala/sttp/client4/armeria/zio/ArmeriaZioBackend.scala
@@ -77,18 +77,18 @@ object ArmeriaZioBackend {
   def layer(options: BackendOptions = BackendOptions.Default): Layer[Throwable, SttpClient] =
     ZLayer.scoped(scoped(options))
 
-  def usingClient(client: WebClient): Task[StreamBackend[Task, ZioStreams]] =
+  def usingClient(client: WebClient, closeFactory: Boolean = false): Task[StreamBackend[Task, ZioStreams]] =
     ZIO
       .runtime[Any]
-      .map(runtime => apply(runtime, client, closeFactory = false))
+      .map(runtime => apply(runtime, client, closeFactory = closeFactory))
 
-  def usingClient[R](runtime: Runtime[R], client: WebClient): StreamBackend[Task, ZioStreams] =
-    apply(runtime, client, closeFactory = false)
+  def usingClient[R](runtime: Runtime[R], client: WebClient, closeFactory: Boolean = false): StreamBackend[Task, ZioStreams] =
+    apply(runtime, client, closeFactory = closeFactory)
 
-  def usingDefaultClient(): Task[StreamBackend[Task, ZioStreams]] =
+  def usingDefaultClient(closeFactory: Boolean = false): Task[StreamBackend[Task, ZioStreams]] =
     ZIO
       .runtime[Any]
-      .map(runtime => apply(runtime, newClient(), closeFactory = false))
+      .map(runtime => apply(runtime, newClient(), closeFactory = closeFactory))
 
   private def apply[R](runtime: Runtime[R], client: WebClient, closeFactory: Boolean): StreamBackend[Task, ZioStreams] =
     wrappers.FollowRedirectsBackend(new ArmeriaZioBackend(runtime, client, closeFactory))
diff --git a/armeria-backend/zio1/src/main/scala/sttp/client4/armeria/zio/ArmeriaZioBackend.scala b/armeria-backend/zio1/src/main/scala/sttp/client4/armeria/zio/ArmeriaZioBackend.scala
index 93d92a2694..b152d70621 100644
--- a/armeria-backend/zio1/src/main/scala/sttp/client4/armeria/zio/ArmeriaZioBackend.scala
+++ b/armeria-backend/zio1/src/main/scala/sttp/client4/armeria/zio/ArmeriaZioBackend.scala
@@ -61,18 +61,18 @@ object ArmeriaZioBackend {
   def layer(options: BackendOptions = BackendOptions.Default): Layer[Throwable, SttpClient] =
     ZLayer.fromManaged(managed(options))
 
-  def usingClient(client: WebClient): Task[StreamBackend[Task, ZioStreams]] =
+  def usingClient(client: WebClient, closeFactory: Boolean = false): Task[StreamBackend[Task, ZioStreams]] =
     ZIO
       .runtime[Any]
-      .map(runtime => apply(runtime, client, closeFactory = false))
+      .map(runtime => apply(runtime, client, closeFactory = closeFactory))
 
-  def usingClient[R](runtime: Runtime[R], client: WebClient): StreamBackend[Task, ZioStreams] =
-    apply(runtime, client, closeFactory = false)
+  def usingClient[R](runtime: Runtime[R], client: WebClient, closeFactory: Boolean = false): StreamBackend[Task, ZioStreams] =
+    apply(runtime, client, closeFactory = closeFactory)
 
-  def usingDefaultClient(): Task[StreamBackend[Task, ZioStreams]] =
+  def usingDefaultClient(closeFactory: Boolean = false): Task[StreamBackend[Task, ZioStreams]] =
     ZIO
       .runtime[Any]
-      .map(runtime => apply(runtime, newClient(), closeFactory = false))
+      .map(runtime => apply(runtime, newClient(), closeFactory = closeFactory))
 
   private def apply[R](runtime: Runtime[R], client: WebClient, closeFactory: Boolean): StreamBackend[Task, ZioStreams] =
     wrappers.FollowRedirectsBackend(new ArmeriaZioBackend(runtime, client, closeFactory))
diff --git a/okhttp-backend/src/main/scala/sttp/client4/okhttp/OkHttpFutureBackend.scala b/okhttp-backend/src/main/scala/sttp/client4/okhttp/OkHttpFutureBackend.scala
index cc4d9011fb..229fc7fd2f 100644
--- a/okhttp-backend/src/main/scala/sttp/client4/okhttp/OkHttpFutureBackend.scala
+++ b/okhttp-backend/src/main/scala/sttp/client4/okhttp/OkHttpFutureBackend.scala
@@ -80,9 +80,10 @@ object OkHttpFutureBackend {
   def usingClient(
       client: OkHttpClient,
       compressionHandlers: CompressionHandlers[Any, InputStream] = DefaultCompressionHandlers,
-      webSocketBufferCapacity: Option[Int] = OkHttpBackend.DefaultWebSocketBufferCapacity
+      webSocketBufferCapacity: Option[Int] = OkHttpBackend.DefaultWebSocketBufferCapacity,
+      closeClient: Boolean = false
   )(implicit ec: ExecutionContext = ExecutionContext.global): WebSocketBackend[Future] =
-    OkHttpFutureBackend(client, closeClient = false, compressionHandlers, webSocketBufferCapacity)
+    OkHttpFutureBackend(client, closeClient = closeClient, compressionHandlers, webSocketBufferCapacity)
 
   /** Create a stub backend for testing, which uses the [[Future]] response wrapper, and doesn't support streaming.
     *
diff --git a/okhttp-backend/src/main/scala/sttp/client4/okhttp/OkHttpSyncBackend.scala b/okhttp-backend/src/main/scala/sttp/client4/okhttp/OkHttpSyncBackend.scala
index 06dd478c66..42231e84c5 100644
--- a/okhttp-backend/src/main/scala/sttp/client4/okhttp/OkHttpSyncBackend.scala
+++ b/okhttp-backend/src/main/scala/sttp/client4/okhttp/OkHttpSyncBackend.scala
@@ -128,9 +128,10 @@ object OkHttpSyncBackend {
   def usingClient(
       client: OkHttpClient,
       compressionHandlers: CompressionHandlers[Any, InputStream] = DefaultCompressionHandlers,
-      webSocketBufferCapacity: Option[Int] = OkHttpBackend.DefaultWebSocketBufferCapacity
+      webSocketBufferCapacity: Option[Int] = OkHttpBackend.DefaultWebSocketBufferCapacity,
+      closeClient: Boolean = false
   ): WebSocketSyncBackend =
-    OkHttpSyncBackend(client, closeClient = false, compressionHandlers, webSocketBufferCapacity)
+    OkHttpSyncBackend(client, closeClient = closeClient, compressionHandlers, webSocketBufferCapacity)
 
   /** Create a stub backend for testing, which uses the [[Identity]] response wrapper, and doesn't support streaming.
     *