diff --git a/Sources/Amplitude/Utilities/HttpClient.swift b/Sources/Amplitude/Utilities/HttpClient.swift
index 2ebda526..a641152b 100644
--- a/Sources/Amplitude/Utilities/HttpClient.swift
+++ b/Sources/Amplitude/Utilities/HttpClient.swift
@@ -72,8 +72,11 @@ class HttpClient {
 
     func getRequestData(events: String) -> Data? {
         let apiKey = configuration.apiKey
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions.insert(.withFractionalSeconds)
+        let clientUploadTime: String = formatter.string(from: getDate())
         var requestPayload = """
-            {"api_key":"\(apiKey)","events":\(events)
+            {"api_key":"\(apiKey)","client_upload_time":"\(clientUploadTime)","events":\(events)
             """
         if let minIdLength = configuration.minIdLength {
             requestPayload += """
@@ -83,6 +86,10 @@ class HttpClient {
         requestPayload += "}"
         return requestPayload.data(using: .utf8)
     }
+
+    func getDate() -> Date {
+        return Date()
+    }
 }
 
 extension HttpClient {
diff --git a/Tests/AmplitudeTests/Supports/TestUtilities.swift b/Tests/AmplitudeTests/Supports/TestUtilities.swift
index da724473..3652ebf7 100644
--- a/Tests/AmplitudeTests/Supports/TestUtilities.swift
+++ b/Tests/AmplitudeTests/Supports/TestUtilities.swift
@@ -129,6 +129,11 @@ class FakeHttpClient: HttpClient {
         completion(Result.success(200))
         return nil
     }
+
+    override func getDate() -> Date {
+        // timestamp of 2023-10-24T18:16:24.000 in UTC time zone
+        return Date(timeIntervalSince1970: 1698171384)
+    }
 }
 
 class FakeResponseHandler: ResponseHandler {
diff --git a/Tests/AmplitudeTests/Utilities/HttpClientTests.swift b/Tests/AmplitudeTests/Utilities/HttpClientTests.swift
index 774746f0..0fc84599 100644
--- a/Tests/AmplitudeTests/Utilities/HttpClientTests.swift
+++ b/Tests/AmplitudeTests/Utilities/HttpClientTests.swift
@@ -42,6 +42,19 @@ final class HttpClientTests: XCTestCase {
         }
     }
 
+    func testGetRequestData() {
+        let httpClient = FakeHttpClient(configuration: configuration)
+        let event = BaseEvent(userId: "unit-test user", eventType: "unit-test event")
+
+        let expectedRequestPayload = """
+            {"api_key":"testApiKey","client_upload_time":"2023-10-24T18:16:24.000Z","events":[\(event.toString())]}
+            """.data(using: .utf8)
+
+        let result = httpClient.getRequestData(events: "[\(event.toString())]")
+
+        XCTAssertEqual(result, expectedRequestPayload)
+    }
+
     func testUploadWithInvalidApiKey() {
         // TODO: currently this test is sending request to real Amplitude host, update to mock for better stability
         let httpClient = HttpClient(configuration: configuration)