diff --git a/MixpanelDemo/MixpanelDemoTests/MixpanelFeatureFlagTests.swift b/MixpanelDemo/MixpanelDemoTests/MixpanelFeatureFlagTests.swift
index 466ad182..0e142e29 100644
--- a/MixpanelDemo/MixpanelDemoTests/MixpanelFeatureFlagTests.swift
+++ b/MixpanelDemo/MixpanelDemoTests/MixpanelFeatureFlagTests.swift
@@ -882,6 +882,56 @@ class FeatureFlagManagerTests: XCTestCase {
     let missingFieldResult = parseResponse(missingFieldJSON)
     XCTAssertNotNil(missingFieldResult, "Parser should handle missing flags field")
     XCTAssertNil(missingFieldResult?.flags, "Flags should be nil when field is missing")
+
+    let optionalExperimentPropertiesJSON = """
+      {
+          "flags": {
+              "active_experiment_flag": {
+                  "variant_key": "A",
+                  "variant_value": "A",
+                  "experiment_id": "447db52b-ec4a-4186-8d89-f9ba7bc7d7dd",
+                  "is_experiment_active": true,
+                  "is_qa_tester": false
+              },
+              "experiment_flag_for_qa_user": {
+                  "variant_key": "B",
+                  "variant_value": "B",
+                  "experiment_id": "447db52b-ec4a-4186-8d89-f9ba7bc7d7dd",
+                  "is_experiment_active": false,
+                  "is_qa_tester": true
+              },
+              "flag_with_no_optionals": {
+                  "variant_key": "C",
+                  "variant_value": "C"
+              }
+          }
+      }
+      """.data(using: .utf8)!
+
+    let experimentResult = parseResponse(optionalExperimentPropertiesJSON)
+    XCTAssertNotNil(experimentResult)
+    XCTAssertEqual(experimentResult?.flags?.count, 3)
+
+    let activeFlag = experimentResult?.flags?["active_experiment_flag"]
+    XCTAssertEqual(activeFlag?.key, "A")
+    XCTAssertEqual(activeFlag?.value as? String, "A")
+    XCTAssertEqual(activeFlag?.experimentID, "447db52b-ec4a-4186-8d89-f9ba7bc7d7dd")
+    XCTAssertEqual(activeFlag?.isExperimentActive, true)
+    XCTAssertEqual(activeFlag?.isQATester, false)
+
+    let qaFlag = experimentResult?.flags?["experiment_flag_for_qa_user"]
+    XCTAssertEqual(qaFlag?.key, "B")
+    XCTAssertEqual(qaFlag?.value as? String, "B")
+    XCTAssertEqual(qaFlag?.experimentID, "447db52b-ec4a-4186-8d89-f9ba7bc7d7dd")
+    XCTAssertEqual(qaFlag?.isExperimentActive, false)
+    XCTAssertEqual(qaFlag?.isQATester, true)
+
+    let minimalFlag = experimentResult?.flags?["flag_with_no_optionals"]
+    XCTAssertEqual(minimalFlag?.key, "C")
+    XCTAssertEqual(minimalFlag?.value as? String, "C")
+    XCTAssertNil(minimalFlag?.experimentID)
+    XCTAssertNil(minimalFlag?.isExperimentActive)
+    XCTAssertNil(minimalFlag?.isQATester)
   }
 
   // --- Delegate Error Handling Tests ---
@@ -1258,6 +1308,23 @@ class FeatureFlagManagerTests: XCTestCase {
     }
   }
 
+  func testTrackingIncludesOptionalProperties() {
+    // Set up flags with experiment properties
+    let flagsWithExperiment: [String: MixpanelFlagVariant] = [
+      "experiment_flag": MixpanelFlagVariant(key: "variant_a", value: true, isExperimentActive: true, isQATester: false, experimentID: "exp_123")
+    ]
+    simulateFetchSuccess(flags: flagsWithExperiment)
+
+    mockDelegate.trackExpectation = XCTestExpectation(description: "Track with experiment properties")
+    _ = manager.getVariantSync("experiment_flag", fallback: defaultFallback)
+    wait(for: [mockDelegate.trackExpectation!], timeout: 1.0)
+
+    let props = mockDelegate.trackedEvents[0].properties!
+    XCTAssertEqual(props["$experiment_id"] as? String, "exp_123")
+    XCTAssertEqual(props["$is_experiment_active"] as? Bool, true)
+    XCTAssertEqual(props["$is_qa_tester"] as? Bool, false)
+  }
+
   // MARK: - Timing Properties Sanity Tests
 
   func testTimingPropertiesSanity() {
diff --git a/Sources/FeatureFlags.swift b/Sources/FeatureFlags.swift
index 23d11022..ec91df94 100644
--- a/Sources/FeatureFlags.swift
+++ b/Sources/FeatureFlags.swift
@@ -33,10 +33,16 @@ struct AnyCodable: Decodable {
 public struct MixpanelFlagVariant: Decodable {
   public let key: String  // Corresponds to 'variant_key' from API
   public let value: Any?  // Corresponds to 'variant_value' from API
+  public let experimentID: String? // Corresponds to 'experiment_id' from API
+  public let isExperimentActive: Bool? // Corresponds to 'is_experiment_active' from API
+  public let isQATester: Bool? // Corresponds to 'is_qa_tester' from API
 
   enum CodingKeys: String, CodingKey {
     case key = "variant_key"
     case value = "variant_value"
+    case experimentID = "experiment_id"
+    case isExperimentActive = "is_experiment_active"
+    case isQATester = "is_qa_tester"
   }
 
   public init(from decoder: Decoder) throws {
@@ -49,16 +55,24 @@ public struct MixpanelFlagVariant: Decodable {
     // If the value is an unsupported type, AnyCodable throws.
     let anyCodableValue = try container.decode(AnyCodable.self, forKey: .value)
     value = anyCodableValue.value  // Extract the underlying Any? value
+
+    // Decode optional fields for tracking
+    experimentID = try container.decodeIfPresent(String.self, forKey: .experimentID)
+    isExperimentActive = try container.decodeIfPresent(Bool.self, forKey: .isExperimentActive)
+    isQATester = try container.decodeIfPresent(Bool.self, forKey: .isQATester)
   }
 
   // Helper initializer with fallbacks, value defaults to key if nil
-  public init(key: String = "", value: Any? = nil) {
+  public init(key: String = "", value: Any? = nil, isExperimentActive: Bool? = nil, isQATester: Bool? = nil, experimentID: String? = nil) {
     self.key = key
     if let value = value {
       self.value = value
     } else {
       self.value = key
     }
+    self.experimentID = experimentID
+    self.isExperimentActive = isExperimentActive
+    self.isQATester = isQATester
   }
 }
 
@@ -570,6 +584,16 @@ class FeatureFlagManager: Network, MixpanelFlags {
       properties["fetchLatencyMs"] = fetchLatencyMs
     }
 
+    if let experimentID = variant.experimentID {
+      properties["$experiment_id"] = experimentID
+    }
+    if let isExperimentActive = variant.isExperimentActive {
+      properties["$is_experiment_active"] = isExperimentActive
+    }
+    if let isQATester = variant.isQATester {
+      properties["$is_qa_tester"] = isQATester
+    }
+
     // Dispatch delegate call asynchronously to main thread for safety
     DispatchQueue.main.async {
       delegate.track(event: "$experiment_started", properties: properties)