diff --git a/client-sdks/reference/flutter.mdx b/client-sdks/reference/flutter.mdx
index 19f93178..df68999f 100644
--- a/client-sdks/reference/flutter.mdx
+++ b/client-sdks/reference/flutter.mdx
@@ -348,10 +348,57 @@ class TodosWidget extends StatelessWidget {
   }
 }
 ```
+
 ## Configure Logging
 
 Since version 1.1.2 of the SDK, logging is enabled by default and outputs logs from PowerSync to the console in debug mode.
 
+To disable this, or to configure logging in release-mode configurations, use the `logger` parameter on the `PowerSyncDatabase` constructor.
+PowerSync uses [`package:logging`](https://pub.dev/packages/logging) to emit logs. See that package for additional information.
+
+## Custom HTTP Clients and Headers
+
+PowerSync uses a streaming HTTP response to connect to the PowerSync service. The SDK uses the default `Client()` from the
+[http package](https://pub.dev/packages/http) for that, which relies on `HttpClient` from `dart:io` on native platforms and `fetch()`
+on the web.
+
+You can also supply a custom HTTP client. This can be used to enable a faster HTTP implementation like [`cronet_http`](https://pub.dev/packages/cronet_http),
+or to add custom request headers that may be required if you run the PowerSync service behind a reverse-proxy.
+
+```dart
+import 'package:http/http.dart';
+import 'package:powersync/powersync.dart';
+
+final class _AddHeaderClient extends BaseClient {
+  final Client inner;
+
+  _AddHeaderClient([Client? inner]) : inner = inner ?? Client();
+
+  @override
+  Future<StreamedResponse> send(BaseRequest request) {
+    request.headers['x-my-custom-header'] = 'set for all requests';
+    return inner.send(request);
+  }
+
+  @override
+  void close() => inner.close();
+}
+
+Future<void> connect(PowerSyncDatabase db) async {
+  await db.connect(
+    connector: MyBackendConnector(db),
+    options: SyncOptions(
+      httpClient: _AddHeaderClient.new
+    ),
+  );
+}
+```
+
+<Note>
+  On the web, PowerSync uses a shared worker for the sync process. As Dart objects cannot be shared between tabs and workers, the worker will use a
+  random tab as a proxy to send requests. This can slow down the sync process slightly.
+</Note>
+
 ## Additional Usage Examples
 
 For more usage examples including accessing connection status, monitoring sync progress, and waiting for initial sync, see the [Usage Examples](/client-sdks/usage-examples) page.
diff --git a/client-sdks/reference/kotlin.mdx b/client-sdks/reference/kotlin.mdx
index a532f07f..389c9db3 100644
--- a/client-sdks/reference/kotlin.mdx
+++ b/client-sdks/reference/kotlin.mdx
@@ -320,6 +320,49 @@ Logger.e("Some error");
 ...
 ```
 
+## Custom HTTP Clients and Headers
+
+PowerSync uses streaming HTTP responses or WebSockets to connect to the PowerSync service. The SDK uses
+[ktor](https://ktor.io/) as a cross-platform HTTP client. `com.powersync:core` depends on an OkHttp-based
+implementation on Android and JVM targets, and on the Darwin engine for native Apple targets.
+
+Configure how the PowerSync SDK sets up client engines by passing an instance of `SyncClientConfiguration.ExtendedConfig`
+in `SyncOptions`:
+
+```kotlin
+import com.powersync.sync.SyncClientConfiguration
+import com.powersync.sync.SyncOptions
+import io.ktor.client.plugins.defaultRequest
+import io.ktor.client.request.header
+
+db.connect(
+    connector,
+    options = SyncOptions(
+        clientConfiguration = SyncClientConfiguration.ExtendedConfig {
+            // For more options, see https://ktor.io/docs/client-create-and-configure.html#plugins
+            defaultRequest {
+                header("X-Custom-Header", "Used by PowerSync")
+            }
+        }
+    )
+)
+```
+
+If you want to use a custom HTTP client engine instead, use `SyncClientConfiguration.ExistingClient`:
+
+```kotlin
+import com.powersync.sync.configureSyncHttpClient
+
+db.connect(
+    connector,
+    options = SyncOptions(
+        clientConfiguration = SyncClientConfiguration.ExistingClient(HttpClient(YourPreferredClientEngine) {
+            // Important: This configures a minimal set of plugins required by the PowerSync sync client.
+            configureSyncHttpClient()
+        })
+    )
+)
+```
 
 ## Additional Usage Examples
 
diff --git a/client-sdks/reference/swift.mdx b/client-sdks/reference/swift.mdx
index 64216339..a202f3fd 100644
--- a/client-sdks/reference/swift.mdx
+++ b/client-sdks/reference/swift.mdx
@@ -277,6 +277,30 @@ let db = PowerSyncDatabase(
 
 The `DefaultLogger` supports the following severity levels: `.debug`, `.info`, `.warn`, `.error`. 
 
+## Custom HTTP Clients and Headers
+
+PowerSync uses a streaming HTTP response to connect to the PowerSync service. By default, the Swift SDK uses `URLSession.shared`
+to run HTTP requests.
+
+You can provide a custom `URLSession` as a sync option. This can be used to add custom HTTP headers, for example:
+
+```swift
+let config = URLSessionConfiguration.ephemeral
+config.httpAdditionalHeaders = ["x-my-custom-header": "example"]
+let session = URLSession(configuration: config)
+
+try await db.connect(
+    connector: connector,
+    options: ConnectOptions(
+        clientConfiguration: SyncClientConfiguration(
+            urlSession: session
+        )
+    )
+)
+```
+
+For more information, see Apple's documentation on [`URLSessionConfiguration`](https://developer.apple.com/documentation/foundation/urlsessionconfiguration).
+
 ## Additional Usage Examples
 
 For more usage examples including accessing connection status, monitoring sync progress, and waiting for initial sync, see the [Usage Examples](/client-sdks/usage-examples) page.