diff --git a/src/apify_client/_models.py b/src/apify_client/_models.py
index 19f5cf6d..57b1db8e 100644
--- a/src/apify_client/_models.py
+++ b/src/apify_client/_models.py
@@ -3766,6 +3766,18 @@ class WebhookRepresentation(BaseModel):
     """
     Optional template for the HTTP headers sent by the webhook.
     """
+    idempotency_key: Annotated[str | None, Field(alias='idempotencyKey', examples=['fdSJmdP3nfs7sfk3y'])] = None
+    """
+    Optional key that prevents creating duplicate webhooks, e.g. when the run-starting request is retried.
+    """
+    ignore_ssl_errors: Annotated[bool | None, Field(alias='ignoreSslErrors', examples=[False])] = None
+    """
+    Optional flag to ignore SSL errors when the webhook sends the request.
+    """
+    do_not_retry: Annotated[bool | None, Field(alias='doNotRetry', examples=[False])] = None
+    """
+    Optional flag to skip retrying the webhook request on failure.
+    """
 
 
 @docs_group('Models')
diff --git a/src/apify_client/_typeddicts.py b/src/apify_client/_typeddicts.py
index fa430ab7..e3e3bbb1 100644
--- a/src/apify_client/_typeddicts.py
+++ b/src/apify_client/_typeddicts.py
@@ -336,6 +336,18 @@ class WebhookRepresentationDict(TypedDict):
     """
     Optional template for the HTTP headers sent by the webhook.
     """
+    idempotency_key: NotRequired[str | None]
+    """
+    Optional key that prevents creating duplicate webhooks, e.g. when the run-starting request is retried.
+    """
+    ignore_ssl_errors: NotRequired[bool | None]
+    """
+    Optional flag to ignore SSL errors when the webhook sends the request.
+    """
+    do_not_retry: NotRequired[bool | None]
+    """
+    Optional flag to skip retrying the webhook request on failure.
+    """
 
 
 @docs_group('Typed dicts')
@@ -374,3 +386,15 @@ class WebhookRepresentationCamelDict(TypedDict):
     """
     Optional template for the HTTP headers sent by the webhook.
     """
+    idempotencyKey: NotRequired[str | None]
+    """
+    Optional key that prevents creating duplicate webhooks, e.g. when the run-starting request is retried.
+    """
+    ignoreSslErrors: NotRequired[bool | None]
+    """
+    Optional flag to ignore SSL errors when the webhook sends the request.
+    """
+    doNotRetry: NotRequired[bool | None]
+    """
+    Optional flag to skip retrying the webhook request on failure.
+    """
diff --git a/src/apify_client/_utils.py b/src/apify_client/_utils.py
index e488b5be..9d8e128e 100644
--- a/src/apify_client/_utils.py
+++ b/src/apify_client/_utils.py
@@ -307,6 +307,9 @@ def encode_webhooks_to_base64(webhooks: WebhooksList | None) -> str | None:
                     request_url=webhook.request_url,
                     payload_template=webhook.payload_template,
                     headers_template=webhook.headers_template,
+                    idempotency_key=webhook.idempotency_key,
+                    ignore_ssl_errors=webhook.ignore_ssl_errors,
+                    do_not_retry=webhook.do_not_retry,
                 )
             )
         else:
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index 7ecf037c..0fcfe08c 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -1,6 +1,8 @@
 from __future__ import annotations
 
 import io
+import json
+from base64 import b64decode
 from datetime import timedelta
 from http import HTTPStatus
 from typing import TYPE_CHECKING
@@ -58,6 +60,33 @@ def test_encode_webhooks_to_base64() -> None:
     )
 
 
+def test_encode_webhooks_to_base64_keeps_adhoc_fields() -> None:
+    """Test that the idempotency key and the SSL/retry flags survive the projection onto `WebhookRepresentation`."""
+    result = encode_webhooks_to_base64(
+        [
+            WebhookCreate(
+                event_types=['ACTOR.RUN.SUCCEEDED'],
+                condition=WebhookCondition(),
+                request_url='https://example.com/run-succeeded',
+                idempotency_key='some-key',
+                ignore_ssl_errors=True,
+                do_not_retry=True,
+            ),
+        ]
+    )
+
+    assert result is not None
+    assert json.loads(b64decode(result)) == [
+        {
+            'eventTypes': ['ACTOR.RUN.SUCCEEDED'],
+            'requestUrl': 'https://example.com/run-succeeded',
+            'idempotencyKey': 'some-key',
+            'ignoreSslErrors': True,
+            'doNotRetry': True,
+        }
+    ]
+
+
 def test_encode_webhooks_to_base64_from_dicts() -> None:
     """Test that encode_webhooks_to_base64 accepts plain dicts typed as WebhookRepresentationDict."""
     webhooks: list[WebhookRepresentationDict] = [