diff --git a/src/main/java/com/clevertap/apns/Notification.java b/src/main/java/com/clevertap/apns/Notification.java
index 1c71be6..9f454a7 100644
--- a/src/main/java/com/clevertap/apns/Notification.java
+++ b/src/main/java/com/clevertap/apns/Notification.java
@@ -37,6 +37,7 @@
 
 import java.io.UnsupportedEncodingException;
 import java.util.HashMap;
+import java.util.Map;
 import java.util.UUID;
 
 /**
@@ -303,6 +304,169 @@ public Builder interruptionLevel(InterruptionLevel interruptionLevel) {
             return this;
         }
 
+        // sound dictionary support
+        @SuppressWarnings("unchecked")
+        private HashMap<String, Object> getOrCreateSoundMap() {
+            Object existing = aps.get("sound");
+            if (existing instanceof HashMap) {
+                return (HashMap<String, Object>) existing;
+            }
+            return new HashMap<>();
+        }
+
+        public Builder sound(Map<String, Object> soundDict) {
+            if (soundDict != null) {
+                aps.put("sound", soundDict);
+            } else {
+                aps.remove("sound");
+            }
+            return this;
+        }
+
+        public Builder soundCritical(int critical) {
+            HashMap<String, Object> map = getOrCreateSoundMap();
+            map.put("critical", critical);
+            aps.put("sound", map);
+            return this;
+        }
+
+        public Builder soundName(String name) {
+            HashMap<String, Object> map = getOrCreateSoundMap();
+            if (name != null) {
+                map.put("name", name);
+            } else {
+                map.remove("name");
+            }
+            aps.put("sound", map);
+            return this;
+        }
+
+        public Builder soundVolume(double volume) {
+            HashMap<String, Object> map = getOrCreateSoundMap();
+            map.put("volume", volume);
+            aps.put("sound", map);
+            return this;
+        }
+
+        // alert dictionary keys
+        public Builder subtitle(String subtitle) {
+            alert.put("subtitle", subtitle);
+            return this;
+        }
+
+        public Builder launchImage(String launchImage) {
+            alert.put("launch-image", launchImage);
+            return this;
+        }
+
+        public Builder titleLocKey(String key) {
+            alert.put("title-loc-key", key);
+            return this;
+        }
+
+        public Builder titleLocArgs(String[] args) {
+            alert.put("title-loc-args", args);
+            return this;
+        }
+
+        public Builder subtitleLocKey(String key) {
+            alert.put("subtitle-loc-key", key);
+            return this;
+        }
+
+        public Builder subtitleLocArgs(String[] args) {
+            alert.put("subtitle-loc-args", args);
+            return this;
+        }
+
+        public Builder locKey(String key) {
+            alert.put("loc-key", key);
+            return this;
+        }
+
+        public Builder locArgs(String[] args) {
+            alert.put("loc-args", args);
+            return this;
+        }
+
+        // additional APS headers
+        public Builder threadId(String threadId) {
+            if (threadId != null) {
+                aps.put("thread-id", threadId);
+            } else {
+                aps.remove("thread-id");
+            }
+            return this;
+        }
+
+        public Builder targetContentId(String id) {
+            if (id != null) {
+                aps.put("target-content-id", id);
+            } else {
+                aps.remove("target-content-id");
+            }
+            return this;
+        }
+
+        public Builder filterCriteria(String criteria) {
+            if (criteria != null) {
+                aps.put("filter-criteria", criteria);
+            } else {
+                aps.remove("filter-criteria");
+            }
+            return this;
+        }
+
+        public Builder staleDate(long date) {
+            aps.put("stale-date", date);
+            return this;
+        }
+
+        public Builder contentState(Map<String, Object> state) {
+            if (state != null) {
+                aps.put("content-state", state);
+            } else {
+                aps.remove("content-state");
+            }
+            return this;
+        }
+
+        public Builder timestamp(long ts) {
+            aps.put("timestamp", ts);
+            return this;
+        }
+
+        public Builder event(String event) {
+            if (event != null) {
+                aps.put("event", event);
+            } else {
+                aps.remove("event");
+            }
+            return this;
+        }
+
+        public Builder dismissalDate(long date) {
+            aps.put("dismissal-date", date);
+            return this;
+        }
+
+        public Builder attributesType(String type) {
+            if (type != null) {
+                aps.put("attributes-type", type);
+            } else {
+                aps.remove("attributes-type");
+            }
+            return this;
+        }
+
+        public Builder attributes(Map<String, Object> attrs) {
+            if (attrs != null) {
+                aps.put("attributes", attrs);
+            } else {
+                aps.remove("attributes");
+            }
+            return this;
+        }
 
         public int size() {
             try {
diff --git a/src/test/java/com/clevertap/apns/NotificationTest.java b/src/test/java/com/clevertap/apns/NotificationTest.java
index 16b37a9..e3ef092 100644
--- a/src/test/java/com/clevertap/apns/NotificationTest.java
+++ b/src/test/java/com/clevertap/apns/NotificationTest.java
@@ -6,6 +6,8 @@
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
 
+import java.util.HashMap;
+import java.util.Map;
 import java.util.stream.Stream;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -104,4 +106,53 @@ void resetInterruptionLevel() {
         assertEquals("{\"aps\":{\"alert\":{}}}", notification2.getPayload());
     }
 
+    @Test
+    void testThreadId() {
+        Notification notification = new Notification.Builder("token")
+            .threadId("tid123")
+            .build();
+        String payload = notification.getPayload();
+        assertTrue(payload.contains("\"thread-id\":\"tid123\""));
+        assertTrue(payload.contains("\"alert\":{}"));
+    }
+
+    @Test
+    void testStaleDate() {
+        Notification notification = new Notification.Builder("token")
+            .staleDate(987654321L)
+            .build();
+        String payload = notification.getPayload();
+        assertTrue(payload.contains("\"stale-date\":987654321"));
+        assertTrue(payload.contains("\"alert\":{}"));
+    }
+
+    @Test
+    void testSoundDictionary() {
+        Map<String, Object> soundDict = new HashMap<>();
+        soundDict.put("name", "my_sound");
+        soundDict.put("critical", 2);
+        Notification notification = new Notification.Builder("token")
+            .sound(soundDict)
+            .build();
+        String payload = notification.getPayload();
+        assertTrue(payload.contains("\"sound\":{"));
+        assertTrue(payload.contains("\"name\":\"my_sound\""));
+        assertTrue(payload.contains("\"critical\":2"));
+    }
+
+    @Test
+    void testAlertLocalization() {
+        Notification notification = new Notification.Builder("token")
+            .titleLocKey("LOC_KEY")
+            .titleLocArgs(new String[]{"arg1","arg2"})
+            .subtitleLocKey("SUB_KEY")
+            .subtitleLocArgs(new String[]{"sub1","sub2"})
+            .build();
+        String payload = notification.getPayload();
+        assertTrue(payload.contains("\"title-loc-key\":\"LOC_KEY\""));
+        assertTrue(payload.contains("\"title-loc-args\":[\"arg1\",\"arg2\"]"));
+        assertTrue(payload.contains("\"subtitle-loc-key\":\"SUB_KEY\""));
+        assertTrue(payload.contains("\"subtitle-loc-args\":[\"sub1\",\"sub2\"]"));
+    }
+
 }
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