diff --git a/apinator/client.py b/apinator/client.py
index b86068b..41ce0a2 100644
--- a/apinator/client.py
+++ b/apinator/client.py
@@ -5,6 +5,7 @@
 from __future__ import annotations
 
 import json
+import platform
 import time
 import urllib.request
 import urllib.error
@@ -17,6 +18,15 @@
 from .errors import ValidationError, AuthenticationError, ApiError
 
 
+def _user_agent() -> str:
+    # Imported here because the package's __init__ imports this module.
+    from . import __version__
+
+    # Cloudflare in front of the API blocks urllib's default
+    # "Python-urllib/x.y" User-Agent (error 1010), so always send our own.
+    return f"apinator-server-python/{__version__} (Python {platform.python_version()})"
+
+
 class Apinator:
     """
     Apinator server SDK client.
@@ -229,6 +239,7 @@ def _request(
 
         # Set headers
         req.add_header('Content-Type', 'application/json')
+        req.add_header('User-Agent', _user_agent())
         req.add_header('X-Realtime-Key', self.key)
         req.add_header('X-Realtime-Timestamp', str(timestamp))
         req.add_header('X-Realtime-Signature', signature)
diff --git a/tests/test_client.py b/tests/test_client.py
index 95365c0..6998b42 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -82,6 +82,8 @@ def test_trigger_single_channel(self):
             assert f"/apps/{TEST_APP_ID}/events" in request.full_url
             assert request.get_header('Content-type') == 'application/json'
             assert request.get_header('X-realtime-key') == TEST_KEY
+            # Cloudflare blocks urllib's default User-Agent (error 1010).
+            assert request.get_header('User-agent').startswith('apinator-server-python/')
 
             # Verify body
             body = json.loads(request.data.decode('utf-8'))