diff --git a/Microsoft.Azure.Cosmos/src/Handler/HandlerConstants.cs b/Microsoft.Azure.Cosmos/src/Handler/HandlerConstants.cs
index 8003ab7ad9..70c083c4a1 100644
--- a/Microsoft.Azure.Cosmos/src/Handler/HandlerConstants.cs
+++ b/Microsoft.Azure.Cosmos/src/Handler/HandlerConstants.cs
@@ -7,6 +7,13 @@ internal static class HandlerConstants
     {
         public const string StartEpkString = "x-ms-start-epk-string";
         public const string EndEpkString = "x-ms-end-epk-string";
-        public const string ResourceUri = "x-ms-resource-uri";
+        public const string ResourceUri = "x-ms-resource-uri";
+
+        public const string RoutedViaProxy = "x-ms-thinclient-route-via-proxy";
+        public const string ProxyStartEpk = "x-ms-thinclient-range-min";
+        public const string ProxyEndEpk = "x-ms-thinclient-range-max";
+
+        public const string ProxyOperationType = "x-ms-thinclient-proxy-operation-type";
+        public const string ProxyResourceType = "x-ms-thinclient-proxy-resource-type";
     }
 }
\ No newline at end of file
diff --git a/Microsoft.Azure.Cosmos/src/ThinClientTransportSerializer.cs b/Microsoft.Azure.Cosmos/src/ThinClientTransportSerializer.cs
new file mode 100644
index 0000000000..bff6c91e9b
--- /dev/null
+++ b/Microsoft.Azure.Cosmos/src/ThinClientTransportSerializer.cs
@@ -0,0 +1,279 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace Microsoft.Azure.Cosmos
+{
+    using System;
+    using System.Buffers;
+    using System.Collections.Generic;
+    using System.IO;
+    using System.Linq;
+    using System.Net;
+    using System.Net.Http;
+    using System.Threading.Tasks;
+    using Microsoft.Azure.Documents;
+    using Microsoft.Azure.Documents.Collections;
+
+    /// <summary>
+    /// The ThinClientTransportSerializer class provides methods for serializing and deserializing proxy requests and responses
+    /// to and from the RNTBD (Remote Network Transport Binary Data) protocol format. This class is used internally within the
+    /// Azure Cosmos DB SDK to handle communication with the backend services.
+    /// </summary>
+    internal static class ThinClientTransportSerializer
+    {
+        private static readonly PartitionKeyDefinition HashV2SinglePath;
+
+        static ThinClientTransportSerializer()
+        {
+            HashV2SinglePath = new PartitionKeyDefinition
+            {
+                Kind = PartitionKind.Hash,
+                Version = Documents.PartitionKeyDefinitionVersion.V2,
+            };
+            HashV2SinglePath.Paths.Add("/id");
+        }
+
+        /// <summary>
+        /// Wrapper to expose a public bufferprovider for the RNTBD stack.
+        /// </summary>
+        public class BufferProviderWrapper
+        {
+            internal BufferProvider Provider { get; set; } = new ();
+        }
+
+        /// <summary>
+        /// Serialize the Proxy request to the RNTBD protocol format.
+        /// Today this takes the HttprequestMessage and reconstructs the DSR.
+        /// If the SDK can push properties to the HttpRequestMessage then the handler above having
+        /// the DSR can allow us to push that directly to the serialization.
+        /// </summary>
+        public static async Task<Stream> SerializeProxyRequestAsync(
+            BufferProviderWrapper bufferProvider,
+            string accountName,
+            HttpRequestMessage requestMessage)
+        {
+            // Skip this and use the original DSR.
+            OperationType operationType = (OperationType)Enum.Parse(typeof(OperationType), requestMessage.Headers.GetValues(HandlerConstants.ProxyOperationType).First());
+            ResourceType resourceType = (ResourceType)Enum.Parse(typeof(ResourceType), requestMessage.Headers.GetValues(HandlerConstants.ProxyResourceType).First());
+
+            Guid activityId = Guid.Parse(requestMessage.Headers.GetValues(HttpConstants.HttpHeaders.ActivityId).First());
+
+            Stream requestStream = null;
+            if (requestMessage.Content != null)
+            {
+                requestStream = await requestMessage.Content.ReadAsStreamAsync();
+            }
+
+            RequestNameValueCollection dictionaryCollection = new ();
+            foreach (KeyValuePair<string, IEnumerable<string>> header in requestMessage.Headers)
+            {
+                dictionaryCollection.Set(header.Key, string.Join(",", header.Value));
+            }
+
+            using DocumentServiceRequest request = new (
+                operationType,
+                resourceType,
+                requestMessage.RequestUri.PathAndQuery,
+                requestStream,
+                AuthorizationTokenType.PrimaryMasterKey,
+                dictionaryCollection);
+
+            if (operationType.IsPointOperation())
+            {
+                string partitionKey = request.Headers.Get(HttpConstants.HttpHeaders.PartitionKey);
+
+                if (string.IsNullOrEmpty(partitionKey))
+                {
+                    throw new InternalServerErrorException("Partition key is missing or empty.");
+                }
+
+                string epk = GetEffectivePartitionKeyHash(partitionKey);
+
+                request.Properties = new Dictionary<string, object>
+            {
+                { "x-ms-effective-partition-key", HexStringUtility.HexStringToBytes(epk) }
+            };
+            }
+            else if (request.Headers[HandlerConstants.ProxyStartEpk] != null)
+            {
+                // Re-add EPK headers removed by RequestInvokerHandler through Properties
+                request.Properties = new Dictionary<string, object>
+            {
+                { WFConstants.BackendHeaders.StartEpkHash, HexStringUtility.HexStringToBytes(request.Headers[HandlerConstants.ProxyStartEpk]) },
+                { WFConstants.BackendHeaders.EndEpkHash, HexStringUtility.HexStringToBytes(request.Headers[HandlerConstants.ProxyEndEpk]) }
+            };
+
+                request.Headers.Add(HttpConstants.HttpHeaders.ReadFeedKeyType, RntbdConstants.RntdbReadFeedKeyType.EffectivePartitionKeyRange.ToString());
+                request.Headers.Add(HttpConstants.HttpHeaders.StartEpk, request.Headers[HandlerConstants.ProxyStartEpk]);
+                request.Headers.Add(HttpConstants.HttpHeaders.EndEpk, request.Headers[HandlerConstants.ProxyEndEpk]);
+            }
+
+            await request.EnsureBufferedBodyAsync();
+
+            using Documents.Rntbd.TransportSerialization.SerializedRequest serializedRequest =
+                Documents.Rntbd.TransportSerialization.BuildRequestForProxy(
+                    request,
+                    new ResourceOperation(operationType, resourceType),
+                    activityId,
+                    bufferProvider.Provider,
+                    accountName,
+                    out _,
+                    out _);
+
+            // TODO: consider using the SerializedRequest directly.
+            MemoryStream memoryStream = new MemoryStream(serializedRequest.RequestSize);
+            await serializedRequest.CopyToStreamAsync(memoryStream);
+            memoryStream.Position = 0;
+            return memoryStream;
+        }
+
+        public static string GetEffectivePartitionKeyHash(string partitionJson)
+        {
+            return Documents.PartitionKey.FromJsonString(partitionJson).InternalKey.GetEffectivePartitionKeyString(HashV2SinglePath);
+        }
+
+        /// <summary>
+        /// Deserialize the Proxy Response from the RNTBD protocol format to the Http format needed by the caller.
+        /// Today this takes the HttpResponseMessage and reconstructs the modified Http response.
+        /// </summary>
+        public static async Task<HttpResponseMessage> ConvertProxyResponseAsync(HttpResponseMessage responseMessage)
+        {
+            using Stream responseStream = await responseMessage.Content.ReadAsStreamAsync();
+
+            (StatusCodes status, byte[] metadata) = await ReadHeaderAndMetadataAsync(responseStream);
+
+            if (responseMessage.StatusCode != (HttpStatusCode)status)
+            {
+                throw new InternalServerErrorException("Status code mismatch");
+            }
+
+            Rntbd.BytesDeserializer bytesDeserializer = new (metadata, metadata.Length);
+            if (!Documents.Rntbd.HeadersTransportSerialization.TryParseMandatoryResponseHeaders(ref bytesDeserializer, out bool payloadPresent, out _))
+            {
+                throw new InternalServerErrorException("Length mismatch");
+            }
+
+            MemoryStream bodyStream = null;
+            if (payloadPresent)
+            {
+                int length = await ReadBodyLengthAsync(responseStream);
+                bodyStream = new MemoryStream(length);
+                await responseStream.CopyToAsync(bodyStream);
+                bodyStream.Position = 0;
+            }
+
+            // TODO: Clean this up.
+            bytesDeserializer = new Rntbd.BytesDeserializer(metadata, metadata.Length);
+            StoreResponse storeResponse = Documents.Rntbd.TransportSerialization.MakeStoreResponse(
+                status,
+                Guid.NewGuid(),
+                bodyStream,
+                HttpConstants.Versions.CurrentVersion,
+                ref bytesDeserializer);
+
+            HttpResponseMessage response = new ((HttpStatusCode)storeResponse.StatusCode)
+            {
+                RequestMessage = responseMessage.RequestMessage
+            };
+
+            if (bodyStream != null)
+            {
+                response.Content = new StreamContent(bodyStream);
+            }
+
+            foreach (string header in storeResponse.Headers.Keys())
+            {
+                if (header == HttpConstants.HttpHeaders.SessionToken)
+                {
+                    string newSessionToken = $"{storeResponse.PartitionKeyRangeId}:{storeResponse.Headers.Get(header)}";
+                    response.Headers.TryAddWithoutValidation(header, newSessionToken);
+                }
+                else
+                {
+                    response.Headers.TryAddWithoutValidation(header, storeResponse.Headers.Get(header));
+                }
+            }
+
+            response.Headers.TryAddWithoutValidation(HandlerConstants.RoutedViaProxy, "1");
+            return response;
+        }
+
+        private static async Task<(StatusCodes, byte[] metadata)> ReadHeaderAndMetadataAsync(Stream stream)
+        {
+            byte[] header = ArrayPool<byte>.Shared.Rent(24);
+            const int headerLength = 24;
+            try
+            {
+                int headerRead = 0;
+                while (headerRead < headerLength)
+                {
+                    int read = await stream.ReadAsync(header, headerRead, headerLength - headerRead);
+
+                    if (read == 0)
+                    {
+                        throw new DocumentClientException("Unexpected end of stream while reading header bytes", HttpStatusCode.Gone, SubStatusCodes.Unknown);
+                    }
+
+                    headerRead += read;
+                }
+
+                uint totalLength = BitConverter.ToUInt32(header, 0);
+                StatusCodes status = (StatusCodes)BitConverter.ToUInt32(header, 4);
+
+                if (totalLength < headerLength)
+                {
+                    throw new InternalServerErrorException("Header length mismatch");
+                }
+
+                int metadataLength = (int)totalLength - headerLength;
+                byte[] metadata = new byte[metadataLength];
+                int responseMetadataRead = 0;
+                while (responseMetadataRead < metadataLength)
+                {
+                    int read = await stream.ReadAsync(metadata, responseMetadataRead, metadataLength - responseMetadataRead);
+
+                    if (read == 0)
+                    {
+                        throw new DocumentClientException("Unexpected end of stream while reading metadata bytes", HttpStatusCode.Gone, SubStatusCodes.Unknown);
+                    }
+
+                    responseMetadataRead += read;
+                }
+
+                return (status, metadata);
+            }
+            finally
+            {
+                ArrayPool<byte>.Shared.Return(header);
+            }
+        }
+
+        private static async Task<int> ReadBodyLengthAsync(Stream stream)
+        {
+            byte[] header = ArrayPool<byte>.Shared.Rent(4);
+            const int headerLength = 4;
+            try
+            {
+                int headerRead = 0;
+                while (headerRead < headerLength)
+                {
+                    int read = await stream.ReadAsync(header, headerRead, headerLength - headerRead);
+
+                    if (read == 0)
+                    {
+                        throw new DocumentClientException("Unexpected end of stream while reading body length", HttpStatusCode.Gone, SubStatusCodes.Unknown);
+                    }
+
+                    headerRead += read;
+                }
+
+                return BitConverter.ToInt32(header, 0);
+            }
+            finally
+            {
+                ArrayPool<byte>.Shared.Return(header);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/ThinClientTransportSerializerTests.cs b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/ThinClientTransportSerializerTests.cs
new file mode 100644
index 0000000000..a111434b2c
--- /dev/null
+++ b/Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/ThinClientTransportSerializerTests.cs
@@ -0,0 +1,113 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace Microsoft.Azure.Cosmos.Tests
+{
+    using Moq;
+    using System;
+    using System.Collections.Generic;
+    using System.IO;
+    using System.Linq;
+    using System.Net;
+    using System.Net.Http;
+    using System.Threading.Tasks;
+    using Microsoft.Azure.Cosmos;
+    using Microsoft.Azure.Documents;
+    using Microsoft.Azure.Documents.Collections;
+    using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+    [TestClass]
+    public class ThinClientTransportSerializerTests
+    {
+        private readonly Mock<ThinClientTransportSerializer.BufferProviderWrapper> mockBufferProviderWrapper;
+        private readonly string testAccountName = "testAccount";
+        private readonly Uri testUri = new Uri("http://localhost/dbs/db1/colls/coll1/docs/doc1");
+
+        public ThinClientTransportSerializerTests()
+        {
+            this.mockBufferProviderWrapper = new Mock<ThinClientTransportSerializer.BufferProviderWrapper>();
+        }
+
+        [TestMethod]
+        public async Task SerializeProxyRequestAsync_ShouldSerializeRequest()
+        {
+            // Arrange
+            HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Get, this.testUri);
+            requestMessage.Headers.Add(HandlerConstants.ProxyOperationType, "Read");
+            requestMessage.Headers.Add(HandlerConstants.ProxyResourceType, "Document");
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.ActivityId, Guid.NewGuid().ToString());
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.PartitionKey, "[\"testPartitionKey\"]");
+
+            // Act
+            Stream result = await ThinClientTransportSerializer.SerializeProxyRequestAsync(
+                this.mockBufferProviderWrapper.Object,
+                this.testAccountName,
+                requestMessage);
+
+            // Assert
+            Assert.IsNotNull(result);
+            Assert.IsInstanceOfType(result, typeof(Stream));
+        }
+
+        [TestMethod]
+        public async Task SerializeProxyRequestAsync_ThrowsException_WhenPartitionKeyIsMissing()
+        {
+            // Arrange
+            HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Get, this.testUri);
+            requestMessage.Headers.Add(HandlerConstants.ProxyOperationType, "Read");
+            requestMessage.Headers.Add(HandlerConstants.ProxyResourceType, "Document");
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.ActivityId, Guid.NewGuid().ToString());
+
+            // Act & Assert
+            await Assert.ThrowsExceptionAsync<InternalServerErrorException>(() =>
+                ThinClientTransportSerializer.SerializeProxyRequestAsync(
+                    this.mockBufferProviderWrapper.Object,
+                    this.testAccountName,
+                    requestMessage));
+        }
+
+        [TestMethod]
+        public async Task SerializeProxyRequestAsync_InvalidOperationType_ThrowsException()
+        {
+            // Arrange
+            HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Get, this.testUri);
+            requestMessage.Headers.Add(HandlerConstants.ProxyOperationType, "InvalidOperation");
+            requestMessage.Headers.Add(HandlerConstants.ProxyResourceType, "Document");
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.ActivityId, Guid.NewGuid().ToString());
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.PartitionKey, "[\"testPartitionKey\"]");
+
+            // Act & Assert
+            await Assert.ThrowsExceptionAsync<ArgumentException>(() =>
+                ThinClientTransportSerializer.SerializeProxyRequestAsync(
+                    this.mockBufferProviderWrapper.Object,
+                    this.testAccountName,
+                    requestMessage));
+        }
+
+        [TestMethod]
+        public async Task SerializeProxyRequestAsync_WithRequestBody_ShouldSerializeRequest()
+        {
+            // Arrange
+            HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Post, this.testUri)
+            {
+                Content = new StringContent("{ \"key\": \"value\" }")
+            };
+            requestMessage.Headers.Add(HandlerConstants.ProxyOperationType, "Create");
+            requestMessage.Headers.Add(HandlerConstants.ProxyResourceType, "Document");
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.ActivityId, Guid.NewGuid().ToString());
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.PartitionKey, "[\"testPartitionKey\"]");
+
+            // Act
+            Stream result = await ThinClientTransportSerializer.SerializeProxyRequestAsync(
+                this.mockBufferProviderWrapper.Object,
+                this.testAccountName,
+                requestMessage);
+
+            // Assert
+            Assert.IsNotNull(result);
+            Assert.IsInstanceOfType(result, typeof(Stream));
+            Assert.IsTrue(result.Length > 0);
+        }
+    }
+}
\ No newline at end of file