diff --git a/api/services/trigger/webhook_service.py b/api/services/trigger/webhook_service.py
index 4b3e1330fd..5c4607d400 100644
--- a/api/services/trigger/webhook_service.py
+++ b/api/services/trigger/webhook_service.py
@@ -33,6 +33,11 @@ from services.errors.app import QuotaExceededError
 from services.trigger.app_trigger_service import AppTriggerService
 from services.workflow.entities import WebhookTriggerData
 
+try:
+    import magic
+except ImportError:
+    magic = None  # type: ignore[assignment]
+
 logger = logging.getLogger(__name__)
 
 
@@ -317,7 +322,8 @@ class WebhookService:
         try:
             file_content = request.get_data()
             if file_content:
-                file_obj = cls._create_file_from_binary(file_content, "application/octet-stream", webhook_trigger)
+                mimetype = cls._detect_binary_mimetype(file_content)
+                file_obj = cls._create_file_from_binary(file_content, mimetype, webhook_trigger)
                 return {"raw": file_obj.to_dict()}, {}
             else:
                 return {"raw": None}, {}
@@ -341,6 +347,18 @@ class WebhookService:
             body = {"raw": ""}
         return body, {}
 
+    @staticmethod
+    def _detect_binary_mimetype(file_content: bytes) -> str:
+        """Guess MIME type for binary payloads using python-magic when available."""
+        if magic is not None:
+            try:
+                detected = magic.from_buffer(file_content[:1024], mime=True)
+                if detected:
+                    return detected
+            except Exception:
+                logger.debug("python-magic detection failed for octet-stream payload")
+        return "application/octet-stream"
+
     @classmethod
     def _process_file_uploads(
         cls, files: Mapping[str, FileStorage], webhook_trigger: WorkflowWebhookTrigger
diff --git a/api/tests/unit_tests/services/test_webhook_service.py b/api/tests/unit_tests/services/test_webhook_service.py
index 920b1e91b6..d788657589 100644
--- a/api/tests/unit_tests/services/test_webhook_service.py
+++ b/api/tests/unit_tests/services/test_webhook_service.py
@@ -110,6 +110,70 @@ class TestWebhookServiceUnit:
             assert webhook_data["method"] == "POST"
             assert webhook_data["body"]["raw"] == "raw text content"
 
+    def test_extract_octet_stream_body_uses_detected_mime(self):
+        """Octet-stream uploads should rely on detected MIME type."""
+        app = Flask(__name__)
+        binary_content = b"plain text data"
+
+        with app.test_request_context(
+            "/webhook", method="POST", headers={"Content-Type": "application/octet-stream"}, data=binary_content
+        ):
+            webhook_trigger = MagicMock()
+            mock_file = MagicMock()
+            mock_file.to_dict.return_value = {"file": "data"}
+
+            with (
+                patch.object(WebhookService, "_detect_binary_mimetype", return_value="text/plain") as mock_detect,
+                patch.object(WebhookService, "_create_file_from_binary") as mock_create,
+            ):
+                mock_create.return_value = mock_file
+                body, files = WebhookService._extract_octet_stream_body(webhook_trigger)
+
+            assert body["raw"] == {"file": "data"}
+            assert files == {}
+            mock_detect.assert_called_once_with(binary_content)
+            mock_create.assert_called_once()
+            args = mock_create.call_args[0]
+            assert args[0] == binary_content
+            assert args[1] == "text/plain"
+            assert args[2] is webhook_trigger
+
+    def test_detect_binary_mimetype_uses_magic(self, monkeypatch):
+        """python-magic output should be used when available."""
+        fake_magic = MagicMock()
+        fake_magic.from_buffer.return_value = "image/png"
+        monkeypatch.setattr("services.trigger.webhook_service.magic", fake_magic)
+
+        result = WebhookService._detect_binary_mimetype(b"binary data")
+
+        assert result == "image/png"
+        fake_magic.from_buffer.assert_called_once()
+
+    def test_detect_binary_mimetype_fallback_without_magic(self, monkeypatch):
+        """Fallback MIME type should be used when python-magic is unavailable."""
+        monkeypatch.setattr("services.trigger.webhook_service.magic", None)
+
+        result = WebhookService._detect_binary_mimetype(b"binary data")
+
+        assert result == "application/octet-stream"
+
+    def test_detect_binary_mimetype_handles_magic_exception(self, monkeypatch):
+        """Fallback MIME type should be used when python-magic raises an exception."""
+        try:
+            import magic as real_magic
+        except ImportError:
+            pytest.skip("python-magic is not installed")
+
+        fake_magic = MagicMock()
+        fake_magic.from_buffer.side_effect = real_magic.MagicException("magic error")
+        monkeypatch.setattr("services.trigger.webhook_service.magic", fake_magic)
+
+        with patch("services.trigger.webhook_service.logger") as mock_logger:
+            result = WebhookService._detect_binary_mimetype(b"binary data")
+
+            assert result == "application/octet-stream"
+            mock_logger.debug.assert_called_once()
+
     def test_extract_webhook_data_invalid_json(self):
         """Test webhook data extraction with invalid JSON."""
         app = Flask(__name__)