diff --git a/data/interfaces/default/notifier_config.html b/data/interfaces/default/notifier_config.html
index 3e0b89a2..43bf3a91 100644
--- a/data/interfaces/default/notifier_config.html
+++ b/data/interfaces/default/notifier_config.html
@@ -243,6 +243,11 @@
                                     </div>
                                     <ul class="submenu">
                                         <li>
+                                            <div class="form-group">
+                                                <label for="${action['name']}_subject">JSON Headers</label>
+                                                <textarea class="form-control" id="${action['name']}_subject" name="${action['name']}_subject" data-parsley-trigger="change" data-autoresize required>${notifier['notify_text'][action['name']]['subject']}</textarea>
+                                                <p class="help-block">Set custom JSON headers.</p>
+                                            </div>
                                             <div class="form-group">
                                                 <label for="${action['name']}_body">JSON Data</label>
                                                 <textarea class="form-control" id="${action['name']}_body" name="${action['name']}_body" data-parsley-trigger="change" data-autoresize required>${notifier['notify_text'][action['name']]['body']}</textarea>
@@ -326,6 +331,15 @@
                                 <p class="help-block">Set custom arguments passed to the script.</p>
                             </div>
                             % elif notifier['agent_name'] == 'webhook':
+                            <div class="form-group">
+                                <label for="test_subject">JSON Headers</label>
+                                <div class="row">
+                                    <div class="col-md-12">
+                                        <textarea class="form-control" id="test_subject" name="test_subject" data-autoresize></textarea>
+                                    </div>
+                                </div>
+                                <p class="help-block">Set custom JSON headers sent to the webhook.</p>
+                            </div>
                             <div class="form-group">
                                 <label for="test_body">JSON Data</label>
                                 <div class="row">
diff --git a/plexpy/notification_handler.py b/plexpy/notification_handler.py
index eb9aee53..5f99ce11 100644
--- a/plexpy/notification_handler.py
+++ b/plexpy/notification_handler.py
@@ -17,6 +17,7 @@
 import arrow
 import bleach
 from collections import Counter, defaultdict
+from functools import partial
 import hashlib
 from itertools import groupby
 import json
@@ -1086,11 +1087,11 @@ def build_notify_text(subject='', body='', notify_action=None, parameters=None,
     if test:
         return subject, body
 
-    custom_formatter = CustomFormatter()
+    str_formatter = partial(str_format, parameters=parameters)
 
     if agent_id == 15:
         try:
-            script_args = [custom_formatter.format(arg, **parameters) for arg in helpers.split_args(subject)]
+            script_args = [str_formatter(arg) for arg in helpers.split_args(subject)]
         except LookupError as e:
             logger.error(u"Tautulli NotificationHandler :: Unable to parse parameter %s in script argument. Using fallback." % e)
             script_args = []
@@ -1098,41 +1099,53 @@ def build_notify_text(subject='', body='', notify_action=None, parameters=None,
             logger.error(u"Tautulli NotificationHandler :: Unable to parse custom script arguments: %s. Using fallback." % e)
             script_args = []
 
-    try:
-        subject = custom_formatter.format(unicode(subject), **parameters)
-    except LookupError as e:
-        logger.error(u"Tautulli NotificationHandler :: Unable to parse parameter %s in notification subject. Using fallback." % e)
-        subject = unicode(default_subject).format(**parameters)
-    except Exception as e:
-        logger.error(u"Tautulli NotificationHandler :: Unable to parse custom notification subject: %s. Using fallback." % e)
-        subject = unicode(default_subject).format(**parameters)
+    elif agent_id == 25:
+        if subject:
+            try:
+                subject = json.loads(subject)
+            except ValueError as e:
+                logger.error(u"Tautulli NotificationHandler :: Unable to parse custom webhook json header data: %s. Using fallback." % e)
+                subject = ''
+        if subject:
+            try:
+                subject = json.dumps(helpers.traverse_map(subject, str_formatter))
+            except LookupError as e:
+                logger.error(u"Tautulli NotificationHandler :: Unable to parse parameter %s in webhook header data. Using fallback." % e)
+                subject = ''
+            except Exception as e:
+                logger.error(u"Tautulli NotificationHandler :: Unable to parse custom webhook header data: %s. Using fallback." % e)
+                subject = ''
 
-    if agent_id == 25:
         if body:
             try:
                 body = json.loads(body)
             except ValueError as e:
-                logger.error(u"Tautulli NotificationHandler :: Unable to parse custom webhook json data: %s. Using fallback." % e)
+                logger.error(u"Tautulli NotificationHandler :: Unable to parse custom webhook json body data: %s. Using fallback." % e)
                 body = ''
-
         if body:
-            def str_format(s):
-                if isinstance(s, basestring):
-                    return custom_formatter.format(unicode(s), **parameters)
-                return s
-
             try:
-                body = json.dumps(helpers.traverse_map(body, str_format))
+                body = json.dumps(helpers.traverse_map(body, str_formatter))
             except LookupError as e:
-                logger.error(u"Tautulli NotificationHandler :: Unable to parse parameter %s in webhook data. Using fallback." % e)
+                logger.error(u"Tautulli NotificationHandler :: Unable to parse parameter %s in webhook body data. Using fallback." % e)
                 body = ''
             except Exception as e:
-                logger.error(u"Tautulli NotificationHandler :: Unable to parse custom webhook data: %s. Using fallback." % e)
+                logger.error(u"Tautulli NotificationHandler :: Unable to parse custom webhook body data: %s. Using fallback." % e)
                 body = ''
 
     else:
         try:
-            body = custom_formatter.format(unicode(body), **parameters)
+            subject = str_formatter(subject)
+        except LookupError as e:
+            logger.error(
+                u"Tautulli NotificationHandler :: Unable to parse parameter %s in notification subject. Using fallback." % e)
+            subject = unicode(default_subject).format(**parameters)
+        except Exception as e:
+            logger.error(
+                u"Tautulli NotificationHandler :: Unable to parse custom notification subject: %s. Using fallback." % e)
+            subject = unicode(default_subject).format(**parameters)
+
+        try:
+            body = str_formatter(body)
         except LookupError as e:
             logger.error(u"Tautulli NotificationHandler :: Unable to parse parameter %s in notification body. Using fallback." % e)
             body = unicode(default_body).format(**parameters)
@@ -1572,6 +1585,13 @@ def lookup_musicbrainz_info(musicbrainz_type=None, rating_key=None, artist=None,
     return musicbrainz_info
 
 
+def str_format(s, parameters):
+    custom_formatter = CustomFormatter()
+    if isinstance(s, basestring):
+        return custom_formatter.format(unicode(s), **parameters)
+    return s
+
+
 class CustomFormatter(Formatter):
     def __init__(self, default='{{{0}}}'):
         self.default = default
diff --git a/plexpy/notifiers.py b/plexpy/notifiers.py
index 9ae5c301..f88b8eeb 100644
--- a/plexpy/notifiers.py
+++ b/plexpy/notifiers.py
@@ -3613,19 +3613,29 @@ class WEBHOOK(Notifier):
                        }
 
     def agent_notify(self, subject='', body='', action='', **kwargs):
+        if subject:
+            try:
+                webhook_headers = json.loads(subject)
+            except ValueError as e:
+                logger.error(u"Tautulli Notifiers :: Invalid {name} json header data: {e}".format(name=self.NAME, e=e))
+                return False
+        else:
+            webhook_headers = None
+
         if body:
             try:
-                webhook_data = json.loads(body)
+                webhook_body = json.loads(body)
             except ValueError as e:
-                logger.error(u"Tautulli Notifiers :: Invalid {name} json data: {e}".format(name=self.NAME, e=e))
+                logger.error(u"Tautulli Notifiers :: Invalid {name} json body data: {e}".format(name=self.NAME, e=e))
                 return False
-
         else:
-            webhook_data = None
+            webhook_body = None
 
         headers = {'Content-type': 'application/json'}
+        if webhook_headers:
+            headers.update(webhook_headers)
 
-        return self.make_request(self.config['hook'], method=self.config['method'], headers=headers, json=webhook_data)
+        return self.make_request(self.config['hook'], method=self.config['method'], headers=headers, json=webhook_body)
 
     def _return_config_options(self):
         config_option = [{'label': 'Webhook URL',