diff --git a/fusionauth-netcore-client/src/io/fusionauth/DefaultRESTClient.cs b/fusionauth-netcore-client/src/io/fusionauth/DefaultRESTClient.cs
index 21e76ff3..9ef1b107 100644
--- a/fusionauth-netcore-client/src/io/fusionauth/DefaultRESTClient.cs
+++ b/fusionauth-netcore-client/src/io/fusionauth/DefaultRESTClient.cs
@@ -19,6 +19,7 @@
 using System.Linq;
 using System.Net;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Text;
 using System.Threading.Tasks;
 using com.inversoft.error;
@@ -28,7 +29,7 @@
 using Newtonsoft.Json.Serialization;
 
 namespace io.fusionauth {
-  class DefaultRESTClient : IRESTClient {
+  public class DefaultRESTClient : IRESTClient {
     public HttpClient httpClient;
 
     public HttpContent content;
@@ -57,6 +58,10 @@ public DefaultRESTClient(string host) {
       httpClient = new HttpClient {BaseAddress = new Uri(host)};
     }
 
+    public DefaultRESTClient(HttpClient incomingHttpClient) {
+      httpClient = incomingHttpClient;
+    }
+
     /**
      * Sets the authorization header using a key
      *
@@ -164,6 +169,7 @@ private string getFullUri() {
     }
 
     private Task<HttpResponseMessage> baseRequest() {
+      httpClient.DefaultRequestHeaders.Clear();
       foreach (var (key, value) in headers.Select(x => (x.Key, x.Value))) {
         // .Add performs additional validation on the 'value' that may fail if an API key contains a '=' character.
         // - Bypass this additional validation for the Authorization header. If we find other edge cases, perhaps 
@@ -228,4 +234,4 @@ public override Task<ClientResponse<T>> goAsync<T>() {
         });
     }
   }
-}
\ No newline at end of file
+}
diff --git a/fusionauth-netcore-client/src/io/fusionauth/FusionAuthClient.cs b/fusionauth-netcore-client/src/io/fusionauth/FusionAuthClient.cs
index 561f01c1..e2d4e106 100644
--- a/fusionauth-netcore-client/src/io/fusionauth/FusionAuthClient.cs
+++ b/fusionauth-netcore-client/src/io/fusionauth/FusionAuthClient.cs
@@ -3300,4 +3300,24 @@ public IRESTClient build(string host) {
       return new DefaultRESTClient(host);
     }
   }
+
+  public class HttpClientBuilder : IRESTClientBuilder
+  {
+    public HttpClient HTTP_CLIENT;
+
+    public HttpClientBuilder(HttpClient httpClient)
+    {
+      HTTP_CLIENT = httpClient;
+    }
+
+    public IRESTClient build(string host)
+    {
+      if (HTTP_CLIENT.BaseAddress == null)
+      {
+        HTTP_CLIENT.BaseAddress = new Uri(host);
+      }
+      return new DefaultRESTClient(HTTP_CLIENT);
+    }
+
+  }
 }
diff --git a/fusionauth-netcore-client/src/io/fusionauth/FusionAuthSyncClient.cs b/fusionauth-netcore-client/src/io/fusionauth/FusionAuthSyncClient.cs
index 9b4a16e8..9437c50d 100644
--- a/fusionauth-netcore-client/src/io/fusionauth/FusionAuthSyncClient.cs
+++ b/fusionauth-netcore-client/src/io/fusionauth/FusionAuthSyncClient.cs
@@ -33,8 +33,8 @@ namespace io.fusionauth {
   public class FusionAuthSyncClient : IFusionAuthSyncClient {
     public readonly FusionAuthClient client;
 
-    public FusionAuthSyncClient(string apiKey, string host, string tenantId = null) {
-      client = new FusionAuthClient(apiKey, host, tenantId);
+    public FusionAuthSyncClient(string apiKey, string host, string tenantId = null, IRESTClientBuilder clientBuilder = null) {
+      client = new FusionAuthClient(apiKey, host, tenantId, clientBuilder);
     }
 
     /**